Only venue managers can create gigs - Gig is managed by is own venue managers only

[#50719171]
Adds rights to band member to create gigs with one of their bands as main_act in whichever venue - Refacto as well

[#50719171]
Adds validation on gig venue and main act depending on current user role

[#50719171]
Adds test for GigsController - but some actions missing

[#50719171]
Fixed tests bug to remove venues and bands after testing uploaders

[#50719171]
Merge pull request #18 from WilfriedDeluche/gigs-access-rights-50719171

[Fixes #50719171] Gigs access rights 50719171
Modify seed for all gigs not being on the same day

[#50838221]
Add scope Upcoming to Gig - Add scope by_search to Gig - Use of upcoming scope depending on current_user role

[#50838221]
Add button in gig view - I18n

[#50838221]
Add unit test for Upcoming Gigs

[#50838221]
Merge pull request #19 from WilfriedDeluche/concerts-date-scope-50838221

[Fixes #50838221] Concerts date scope 50838221
Merge branch 'master' into test-rails-erd