This patch fixes broken dependencies installed via
python-mysqldb which needs mysql-common-5.7.

Signed-off-by: Ondrej Vasko <ondrej.vaskoo@gmail.com>

Mitaka staging test repository for test-kitchen was
missing KEY_ID which prevented apt-get update to
run successfuly.

Signed-off-by: Ondrej Vasko <ondrej.vaskoo@gmail.com>

Galera repository has changed in upstream and has
divided wsrep and galera directories.
This patch sets up 2 repositories `galera-3` and
`mysql`wsrep-5.6`.

Signed-off-by: Ondrej Vasko <ondrej.vaskoo@gmail.com>

Make max_connections and innodb_buffer_pool_size configurable
through soft params instead of hard.

Change-Id: Id0bb8f6b6091289275864bf4dd6a6890d11b4782