ENH: initial .travis.yml -- needs clarifications on "installation"

Since you guys have tests (few of which actually failed for me) decided that it would be even better if you had used travis-ci.  Please enable it for pyhrf (just go to travis-ci.org, login via github, go to your account, enable for pyhrf), and look into adopting this proposed .travis.yml.

atm local installation  fails, see: https://travis-ci.org/yarikoptic/pyhrf/jobs/21147965 and I haven't had a moment to dig inside to address this peculiarity