CLN: Prepare for 0.7.0 release

[addisonlynch]

Tasks

• Removed EDGAR (support ended 12/2017, deprecated in 0.6.0)
• Repaired Alpha Vantage naming (AlphaVantage -> Alpha Vantage)
• Changed all pause defaults to 0.1. These varied across readers likely due to writing from different contributors
• Cleaned Google test deprecation

Questions

• Should we remove Google? It was also deprecated in 0.6.0 and has not been repaired. This may end some confusion/issues.
• Should wrapt be moved to "test dependencies?" It is currently listed and installed as a core dependency, but only used in tests.

@bashtage let me know if there's anything else you need in preparation for the release.

• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• added entry to docs/source/whatsnew/vLATEST.txt