added coverage and pep8 checks

* integration with coveralls
* check pep8 with flake8
* fixed pep8 to pass, for now we use max-line 90 & two issues are ignored until decided otherwise:
    * disabled E701 (multiple statements on one line) and E126 (continuation line over-indented for hanging indent)
* as now pep8 passes (and is quite loose), it can be activated to impact travis build status

Note: based on https://github.com/petrblaho/python-tuskarclient/blob/master/