Conditional crypto

Add support for crypto based on Ubuntu 12.04+14.04 and RedHat(+derivates) 6.4+6.5.
They should work with the updated test-suite.
Also add Ubuntu 14.04 to kitchen.yml.

Notice: The actual crypto implementation is done in a special function. I chose this way after trying it in raw puppet and realized that the syntax was much more complex and less readable. Doing it in ruby allowed for some more expressive powers and reuse and is from my perspective more expandable. It also reduced the puppet part to the bare necessities.

Complete with some spec tests.