MAINT: Start of 0.8.0 development

Merge pull request #658 from bashtage/074-py27-fixes

MAINT: Restore Python 2.7 compat

Merge pull request #657 from bashtage/702

BUG: Remove pandas.compat dependencies

StringIO in pandas.compat change to import from io

Merge pull request #653 from redpoint13/master

Fix StringIO import

Merge pull request #577 from bashtage/xfail-yahoo-actions

BUG: Yahoo actions adjustment is incorrect

Merge pull request #481 from bashtage/finish-doctr

DOC: Configure doctr to automatically build docs

Merge pull request #375 from davidastephens/REL_050

REL: Release 0.5.0

Version 0.4.0

Merge pull request #277 from davidastephens/rel_0301

REL: Version to v0.3.0.post / update docs