Adds .rspec file with config for pretty output

closes #22
Merge pull request #28 from petrblaho/pretty-rspec

Adds .rspec file with config for pretty output
Setup travis (cucumber, rspec)
Merge pull request #30 from jistr/travis

Setup Travis (cucumber, rspec)
Adds codeclimate badge to readme
Merge pull request #31 from petrblaho/codeclimate-badge

Adds codeclimate badge to readme
Travis status image in readme
Merge pull request #32 from jistr/travis_status

Travis status image in readme
Output: select fields you want for listings

Closes #24.

There is one gotcha. When user writes the option mistakenly like
`--fields`, Thor automatically parses it the same way as if user had
written `--fields=fields`, even though the `fields` option is configured
to type `string`, so it should not be treated like a switch imho. Seems
to me more like a bug than a feature, but I don't know how to write a
*clean* wrokaround, so I'd rather keep it this way for now.
Merge pull request #34 from jistr/output_filtering_rev2

Output: select fields you want for listings