Update ipfshttpclient dependency to ipfshttpclient4ipwb

[machawk1]

This is due to ipfshttpclient not pushing a new release to pypi and ipwb needing to be compatible with newer go-ipfs binaries, which the currently released (to pypi) version of ipfshttpclient is not.

[codecov]

Codecov Report

Merging #662 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #662   +/-   ##
=======================================
  Coverage   27.28%   27.28%           
=======================================
  Files           7        7           
  Lines        1246     1246           
  Branches      191      191           
=======================================
  Hits          340      340           
  Misses        881      881           
  Partials       25       25           

Impacted Files	Coverage Δ
setup.py	0.00% <ø> (ø)
ipwb/backends.py	91.48% <100.00%> (ø)
ipwb/indexer.py	50.57% <100.00%> (ø)
ipwb/replay.py	13.94% <100.00%> (ø)
ipwb/util.py	35.21% <100.00%> (ø)

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[ibnesayeed]

LGTM! Though we could have created an alias when importing to avoid unnecessary renaming in the main code body when referencing the module.

[machawk1]

I agree. This is mainly applicable to {test-}backends.py, as the other scripts seem to have aliases in-place. I think the simple change in this PR will make reverting the name easy going forward when ipfshttpclient pushes another release to pypi.