CI branch merges and random information updates

[Harald Sitter]

ahoy ahoy

random things of interest:

# apps
all applications repos that had a kubuntu_unstable branch now had
their _unstable merged into _stable. i.e. stable is now tracking the
upcoming Applications/15.08.
you *must not* merge stable into a branch from which you want to
release a 15.04 release.

# plasma
plasma 5.4 tagging is supposed to happen tomorrow. shortly after that
kubuntu_stable of all plasma repos will get kubuntu_unstable merged.
i.e. same thing: stable is going to track Plasma/5.4 soon

# deprecations
breeze-qt4 and oxygen-qt4 are now gone entirely from CI as they were
folded into the breeze and oxygen packaging respectively

# symbols reminder
please do not twiddle symbol files in release branches (.e.g
kubuntu_wily_archive). if a symbol file is not uptodate then this is
nothing more than a symptom of a deeper problem and I'd appreciate
putting the time and effort towards solving the underlying problem
rather than apply temporary fixes that confuse the CI

HS