Convert documentation to ReadTheDocs

[pipermerriam]

What was wrong?

Docs are currently only in the README.

How can it be fixed?

Convert documentation to be sphinx based and host on readthedocs.

[carver]

While converting to RTD, we got some reasonable feedback at Devcon4 about what's not working well, currently:

The quick start doesn't actually show how to instantiate a contract or call contract methods, just send basic transactions. Compare that with the documentation on pyethereum tester, which, while extremely scant and not nearly verbose enough, at least tells you how to do what you want to do: https://github.com/ethereum/pyethereum/wiki/Using-pyethereum.tester

Yup, definitely need more content here.

The Eth-Tester readme is also too long and doesn't actually tell you anything. For example, I can read the source if I want to know what the function parameters are to the EthereumTester.take_snapshot function - that level of documentation belongs in the docstring above the function NOT in a ReadMe.

I think the best way to do this is to add docstrings, and have those get auto-inserted into the RTD API docs. So we will end up with low-level docs in RTD, but they will be auto-generated from the source docs.

[pipermerriam]

cc @AKewlBreeze this might be a good one for you.