storage: Add new events for *PoolBuild() and *PoolDelete().

storage: Add new events for *PoolBuild() and *PoolDelete().

This commit adds new events for two methods and operations: *PoolBuild() and
*PoolDelete(). Using the event-test and the commands set below we have the
following outputs:

$ sudo ./event-test
Registering event callbacks
myStoragePoolEventCallback EVENT: Storage pool test Defined 0
myStoragePoolEventCallback EVENT: Storage pool test Created 0
myStoragePoolEventCallback EVENT: Storage pool test Started 0
myStoragePoolEventCallback EVENT: Storage pool test Stopped 0
myStoragePoolEventCallback EVENT: Storage pool test Deleted 0
myStoragePoolEventCallback EVENT: Storage pool test Undefined 0

Another terminal:
$ sudo virsh pool-define test.xml
Pool test defined from test.xml

$ sudo virsh pool-build test
Pool test built

$ sudo virsh pool-start test
Pool test started

$ sudo virsh pool-destroy test
Pool test destroyed

$ sudo virsh pool-delete test
Pool test deleted

$ sudo virsh pool-undefine test
Pool test has been undefined

This commits can be a solution for RHBZ #1475227.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1475227

Signed-off-by: Julio Faracco <jcfaracco@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>