Use a more flexible rubygem requirement syntax (bnc#895069)

https://en.opensuse.org/openSUSE:Packaging_Ruby#Format_of_automatically_generated_Provides:_headers
Merge pull request #24 from yast/rubygem-requires

Use a more flexible rubygem requirement syntax (bnc#895069)
adapt Rakefile to submit to correct build service project in maintenance branch SLE-12-GA
Revert "adapt Rakefile to submit to correct build service project in maintenance branch SLE-12-GA"

This reverts commit 0437cee7ded0db5e72ef435943068bdd47897782.
added README.md with build status badges
removed unnecessary BuildRequires
changes

- 3.1.19
added .travis.yml
fixed test
Merge pull request #26 from yast/build_requires

Build requires clenup
Merge pull request #25 from yast/Travis

Travis support
use a shared script in .travis.yml
proper maintenance target
.travis.yml - use the SLE12 script in the SLE12 branch
added more checks in .travis.yml
Merge remote-tracking branch 'origin/SLE-12-GA'

Conflicts:
	.travis.yml
	Rakefile