Travis CI tests in Python 2.7 and 3.5

[agitter]

Updates .travis.yml to run tests in a conda 2.7 and 3.5 environment as discussed in #26. The unit tests currently fail in Python 3.5. I allowed edits from maintainers in case you want to push to this branch, or you could create a new branch and merge there instead of master.

[agitter]

I added a trivial test case to help me debug an error I had with SequenceDNN.plot_architecture. Even though pip installed Shapely, the line from shapely.wkt import loads as load_wkt gave me:

OSError: Could not find lib geos_c or load any of its variants ['libgeos_c.so.1', 'libgeos_c.so'].

The Travis CI server didn't have a problem with the Shapely import in my test case so it must be specific to my system. Installing Shapely with conda helped, so I added that to .travis.yml even though it is only required for some (older?) systems.

[jisraeli]

@agitter: Thank you for reporting this issue. test_architectures.py was failing in Python 3.5 because the results of the model differed from Python 2.7, likely due to random seed difference. I added the expected results for python 3.5 and the tests now pass with both versions.