Added one exception and few methods in PushManager...
Added new items to csproj

Signed-off-by: Nikola Maric <Nikola.Maric@infobip.com>
Merge branch 'master' of https://github.com/maricn/InfobipApiPush
refactored channel info models

Signed-off-by: Nikola Maric <Nikola.Maric@infobip.com>