Add call context change in hooks
Changed context handling from hooks to prolog

- New file context.pl for context prolog.
- Removed call context handling in hooks and created context target for prolog
- Added context module to be loaded in policy.pl
Merge pull request #1 from tihonko/master

Add call context change in hooks
[policy] Add policy related dbus config.
Merge branch 'master' into n950
[packaging] Add rpm packaging.