Missing keyword in string formatter (just not assigned)
Add test.
Add test for dates in mpl.
Accept any dateformatter! 'DateFormatter' is always in the string.

There might be a super class we could test the instance of, but
this is easy enough for now.
More stable mpl_date conversion, just needs a timezone. (see below).

pytz is a dependency of matplotlib, so this isn't adding bloat to
our optional dependency list.
Merge pull request #127 from plotly/andrew-fix-to-string

Missing keyword in string formatter (just not assigned)
Merge pull request #130 from plotly/andrew-fix-pandas-date-formatter

Andrew fix pandas date formatter
Add a new exception class and test to ensure new expected error.
Add check for empty data and raise helpful message.
updated graph ref?
version bump
Merge pull request #133 from plotly/graph_reference_update

updated graph ref?
Merge pull request #131 from plotly/andrew-better-empty-data-error

Andrew better empty data error
Add a get_config() function to plotly.py.
Add a test for get_config()
Switch over how plotly.py gets config info to use get_config.
Add sign_in test with config info.
get_credentials now ignores user-supplied 'falsey' values
Remove unnecessary 'global' statements
Add get_config to the list of public functions for plotly.py