Provide decorator module in travis

Signed-off-by: Matthias Kümmerer <matthias@matthias-k.org>
Merge pull request #34 from matthias-k/master

Provide decorator module in travis
kurtosis added
Merge pull request #33 from tomwallis/master

Added function `moment`
Merge branch 'master' of https://github.com/fabiansinz/PyCircStat
added kurtosis with tests
added vector_strength synonym for resultant_vector_length
vector_strength_spectrum added
Merge pull request #35 from fabiansinz/master

Kurtosis, renamed tests, more docu