Proposed Travis configuration

Hey Freddy, I've changed the travis configuration. Since tests for room.py are now written for scipy 0.14 I changed the configuration to test against this version. Also, I added an option to test with optional dependencies (only pandas right now). I've kept tests against python 2.7 and 3.4, so there are four builds for each numpy version. Maybe it is a good idea to test for numpy 1.8 because is in Ubuntu 14.04 repositories. If we test with numpy 1.8 there will be 8 build (or 6 if we don't count optional dependencies). Obviously this is not problem for Travis, so we can add more jobs. What do you think?

If you agree with the changes in this pr, please merge it.