[Push] refactored module for using multiple managers

[Push] refactored module for using multiple managers

[Feature] This commit is the first step for applying new policy
  about push module. There would be used different behaviour, dependant
  to current version of application. Currently module was refactored to
  hold tizen 2.4 behaviour. Tizen 3.0 would be implemented in next commits.

[Verification] Code compiles without errors.
  Passrate didn't change.

Change-Id: If26e03352db134b2a5fb5b1a8def46343732c41b
Signed-off-by: Piotr Kosko <p.kosko@samsung.com>