Add methods to resource classes

Resource classes of managers should have methods
like delete() and get(). Basicly base.Resource
class has method get(), which uses id attribute,
but classes Alarm, Event, etc. have no this attribute.
Added intercept getting of id in the resource classes.
Also added catch of HTTPNotFound for alarm get()
because it affects correct functionality of
scenario tests.

Closes-Bug: #1312146
Change-Id: Ie598b73c64dece2185955467936dc6544a8a3dc7
Merge "Add methods to resource classes"