Cinnamon Theme - Update to use spacing & cleanup.

[smurphos]

• use spacing var in menu, panel, buttons and entries
• reviewed other hard-coded padding / spacing / margins
• clean up selectors confirmed as deprecated
• removed obsolete cinnamenu workarounds
• code style - ensure @extend commands are first

[smurphos]

Looks like the docker container failed to update all the necessary packages. Not sure if it can be kicked into trying again? I've built locally following this commit so there shouldn't be any problems.

[actionless]

i need to find a way to make Restart build button available for you in Travis

i wasn't configuring permissions yet, i think now it's the time :-)

[actionless]

after restart it's still failing, i think there is some problem with the current mirrorlist (the server seems to be not accessible well from the travis's datacenter), i'll try to alter it and see if it helps

[smurphos]

I can merge..... ;-)