fix arcane error messages that dropped the context

version increment

backwards compatibility fix for python 3.6

Merge branch 'master' of https://github.com/meraki-analytics/datapipelines

updated to work with python 3.7

Update README.rst

Merge branch 'master' of https://github.com/meraki-analytics/datapipelines

incrementing version to be consistent with current pypi release

update version

missed a NoConversionError except in my prev commit

Prevent duplicate puts to a sink if both the before/after types of a source handler can be converted to a type the sink accepts

made it compatible with networkx 1.x and 2.x

Revert "added `context` parameter to a few places because it was missing"

added `context` parameter to a few places because it was missing

for some reason these two return types are not compatible with py3.5 typing