use anaconda to install dependencies for travis ci

This is inspired by https://gist.github.com/dan-blanchard/7045057 with the goal of testing against multiple Python versions.
install setuptools via conda for travis ci
install pillow via conda and use Python 3.4 as test target
Merge branch 'issue80-conda' of github.com:neothemachine/nansat into neothemachine-issue80-conda
Merge branch 'neothemachine-issue80-conda' into develop