Clean Up Pac Versions [2/3]

Remove Pac version from common make file, as it's unflexible.
Set the Version variables from our main script so that they are properly inherited.

PS2: our own little D-D-Derp here too. + define variables at top of build script.
PS3: Set default to Dev.
PS7: Final update fix sed throw up.

Starting now with Kitkat, individual builds are identified with a build
code, e.g. KK RC3 Nightly.

The first two letters are the code name of the release family.
[e.g. KK is Kitkat, LP is Lolipop]

The third letter is a release code that allows Pac to identify the exact code
tag that the build was made from.
V is primary release branch
RC is release client
B is beta
A is alpha

The third is the 'maitnence' tag. [Dev, Nightly, Weekly]

Change-Id: I41ff3645b8968da7295fe1fae7374f004f508950