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 #32 from yast/rubygem-requires

Use a more flexible rubygem requirement syntax (bnc#895069)
deprecate maintainer file
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 85d9fbd1725c3755233f38e4d105cfbf4ae10f30.
added README.md with build status badges
added .travis.yml
Merge pull request #34 from yast/Travis

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

Conflicts:
	.travis.yml
	Rakefile
remove X-KDE-Library (bnc#899104)
release