travis.ci setup
changed unit test structure (relative imports)
changed discover test method from nose to native unittest
Revert "changed unit test structure (relative imports)"

This reverts commit f731bb94b523a00b5dc529a2f7fc394c6934bba8.
more relative import changes
more relative import changes
more relative import changes
fixed / skipped unit tests
changed aserrtequal to almost equal for float test on sun
code looks for mol weight tag before assuming