update .travis.yml
Updates to drawing/editing

- improved algorithm for selecting lines
- new coordinate mapping classes to support different mapping methods
Added __version__ attribute to module

- updated minor version and release numbers
Merge branch 'travis-ci-update' of https://github.com/cdeil/ginga into cdeil-travis-ci-update
Change `== None` to `is None`
Uncomment egg_info check in .travis.yml again
Fixed bug with certain drawing operations

- fixed a bug to use the viewer's mapping operation if non was supplied
  by the canvas object
Merge branch 'is_none' of https://github.com/cdeil/ginga into cdeil-is_none
Added "is not None" PEP8 fixes to a few examples
Merge branch 'cdeil-is_none'
Removed some spurious initialization errors

- removed some errors that show up in the log when ginga is started up and
  there is no image loaded
- bumped release
Fixed a bug in Catalogs plugin for an initialization error

- fixed a bug where the Catalogs plugin (reference viewer) would throw
  an exception when initializing if no image is present
Addressed a number of small issues

- removed multiple method signatures from two classes
- fixed an initialization exception when window is not yet mapped
- fix for using matplotlib based viewer with qt5agg backend
- fix for loading files in io_fits.py