[#247] update validations

Conflicts:
	app/models/product_build_list.rb
[#247] fix model specs
[#247] add some api specs
[#247] fix build list spec
Merge pull request #441 from abf/rosa-build:247-update_validations
 #247 update validations
update a access rights for creation/build of build_lists
Merge branch 'master' into improvements-of-security
[#369] update project pull requests page
[#369] update a project issues/pull_requests page
[#369] fix project issues page
add maintainer to the project partial
[#369] fix error with new issue page
[#369] new issue page: labels; small fixes
#369: updated UI for Issues#show
#369: cleanup
[#369] new issue page; small fixes
[#369] add select label
[#369] remove small class on a markdown help
[#369] new issue page: add name to the assignee
[#369] new issue page: fix form for a simple user