Ensure that we don't install Python 2.7.9 on Travis (use 2.7.8 instead) otherwise we get certificate erros due to the changes to certificate verification in 2.7.9 (see PEP 476).
Merge pull request #3202 from astrofrog/fix-conda

Disable conda update since latest version breaks SSL certificate checks
Upgrade to wcslib 4.25
Merge pull request #3204 from mdboom/wcs/upgrade-4_25

Upgrade to wcslib 4.25
Initial commit of plotting.py, which will house set_astropy_plot_style(), a function that will set basic mpl.rcParams.
Added matplotlibrc parameters to adopt an astropy plotting style.  The parameters reflect those found in astropy-tutorials.  This is in regards to issue #2719.
Added a version argument and placed the rcparams in a dictionary so that future styles can easily be added.
modify astropy plotting style according to discussion in #2787

This PR is meant to superceed the work in #2787. To this end, it is based on the
commits in that PR so that the original author will receive all due credit.

closes #2787
closes #2719
fix trailing whitespace