orderbook: Make OrderStore async for use in db adapter

[dekz]

Description

We want to adapt the orderstore to fetch from a local database rather than in-memory for usage with 0x API and AssetSwapper. 0xProject/0x-api#33

As such this change moves a number of OrderStore functions to be async. This is not a directly used class and all of OrderBook functions are already async. As are OrderSet since it calculates orderHash async.

Also fixes an issue in asset-swapper where the gas price estimate from ethgastation is in gwei. All calculations based off of that result in gwei as well. This is results in an underfunded protocolFee when a real gas price is used (8 gwei in wei rather than 8 wei).

TODO

• Update changelogs

[buildsize]

File name	Previous Size	New Size	Change
init.py	60.25 KB	60.25 KB	0 bytes (0%)
abi_gen_dummy.ts	77.76 KB	[deleted]
lib_dummy.ts	7.13 KB	[deleted]
test_lib_dummy.ts	10.38 KB	[deleted]
environment.pickle	1.61 MB	1.61 MB	0 bytes (0%)
index.doctree	187.37 KB	187.37 KB	0 bytes (0%)
.buildinfo	230 bytes	230 bytes	0 bytes (0%)
genindex.html	5.6 KB	5.6 KB	0 bytes (0%)
index.html	2.52 KB	2.52 KB	0 bytes (0%)
objects.inv	375 bytes	375 bytes	0 bytes (0%)
py-modindex.html	3.07 KB	3.07 KB	0 bytes (0%)
search.html	2.84 KB	2.84 KB	0 bytes (0%)
searchindex.js	6.31 KB	6.31 KB	0 bytes (0%)
index.rst.txt	415 bytes	415 bytes	0 bytes (0%)
alabaster.css	10.92 KB	10.92 KB	0 bytes (0%)
basic.css	11.89 KB	11.89 KB	0 bytes (0%)
custom.css	42 bytes	42 bytes	0 bytes (0%)
doctools.js	9.05 KB	9.05 KB	0 bytes (0%)
documentation_options.js	303 bytes	303 bytes	0 bytes (0%)
file.png	286 bytes	286 bytes	0 bytes (0%)
jquery-[version].js	273.79 KB	273.79 KB	0 bytes (0%)
jquery.js	86.08 KB	86.08 KB	0 bytes (0%)
language_data.js	10.59 KB	10.59 KB	0 bytes (0%)
minus.png	90 bytes	90 bytes	0 bytes (0%)
plus.png	90 bytes	90 bytes	0 bytes (0%)
pygments.css	4.69 KB	4.69 KB	0 bytes (0%)
searchtools.js	15.61 KB	15.61 KB	0 bytes (0%)
underscore-[version].js	34.34 KB	34.34 KB	0 bytes (0%)
underscore.js	11.86 KB	11.86 KB	0 bytes (0%)
contract_addresses.html	16.8 KB	16.8 KB	0 bytes (0%)
contract_artifacts.html	8.24 KB	8.24 KB	0 bytes (0%)
json_schemas.html	12.56 KB	12.56 KB	0 bytes (0%)
order_utils.html	47.16 KB	47.16 KB	0 bytes (0%)
erc20_token.html	93.56 KB	93.56 KB	0 bytes (0%)
exchange.html	718.38 KB	718.38 KB	0 bytes (0%)
tx_params.html	9.41 KB	9.41 KB	0 bytes (0%)
local_message_signer.html	15.08 KB	15.08 KB	0 bytes (0%)
asset_data_utils.html	22.66 KB	22.66 KB	0 bytes (0%)
default_api.html	113.17 KB	113.17 KB	0 bytes (0%)
asset_proxy_owner.html	337.39 KB	337.39 KB	0 bytes (0%)
coordinator.html	128.72 KB	128.72 KB	0 bytes (0%)
coordinator_registry.html	39.59 KB	39.59 KB	0 bytes (0%)
dutch_auction.html	66.13 KB	66.13 KB	0 bytes (0%)
erc20_proxy.html	109.07 KB	109.07 KB	0 bytes (0%)
erc721_proxy.html	109.19 KB	109.19 KB	0 bytes (0%)
erc721_token.html	150.2 KB	150.2 KB	0 bytes (0%)
forwarder.html	124.01 KB	124.01 KB	0 bytes (0%)
i_asset_proxy.html	40.18 KB	40.18 KB	0 bytes (0%)
i_validator.html	27.06 KB	27.06 KB	0 bytes (0%)
i_wallet.html	24.9 KB	24.9 KB	0 bytes (0%)
multi_asset_proxy.html	144.04 KB	144.04 KB	0 bytes (0%)
order_validator.html	107.69 KB	107.69 KB	0 bytes (0%)
weth9.html	132.09 KB	132.09 KB	0 bytes (0%)
zrx_token.html	107.61 KB	107.61 KB	0 bytes (0%)
dev_utils.html	526.89 KB	526.89 KB	0 bytes (0%)
types.html	8.54 KB	8.54 KB	0 bytes (0%)
erc1155_mintable.html	276.51 KB	276.51 KB	0 bytes (0%)
erc1155_proxy.html	130.38 KB	130.38 KB	0 bytes (0%)
static_call_proxy.html	34.04 KB	34.04 KB	0 bytes (0%)

[coveralls]

Coverage remained the same at 77.804% when pulling 7c08143 on feature/orderbook-orderstore-async into 6b0f357 on development.