Make "testedfiles" work on Ruby files (bnc#819137).

1) Honor "#" comments

These have been working in YCP:
// testedfiles: ...
/* testedfiles: ... */
/*
testedfiles: ...
*/

But Ruby uses(*)
# testedfiles: ...

2) Accept .rb extension: not sure if it actually works but it is
future-proof.

*) https://github.com/yast/y2r/commit/1a8c84e3450ab458622f08c62f7afe492e529312
version+changes
Merge pull request #4 from mvidner/master

 Make "testedfiles" work on Ruby files (bnc#819137).