Utilizes assertIsNone and assertIsNotNone

Using assertEqual/assertNotEqual to test if an element
is or is not None is too python2.4.
Our unit testing framework supports assertIsNone and assertIsNotNone
which were created for these types of tests.

Change-Id: Ieba2d4ce5602885dc8a33a938a40f3086879b2c3
1st & last sample timestamps in Resource representation

Fixes bug 1262335

Previously, the first and last sample timestamps associated
with a resource were calculated by the storage driver, but
then discarded.

Now, we include these values in the API resource representation.

Change-Id: I3cf6081e1ac1294083f6326f85dabebab0d02203
AlarmChange definition added to doc/source/webapi/v2.rst

Change-Id: I0c071a81ddd7a0e5a7083af9077ec20dce0a0b7c
Closes-Bug: #1266519
Merge "AlarmChange definition added to doc/source/webapi/v2.rst"
Merge "1st & last sample timestamps in Resource representation"
Merge "Utilizes assertIsNone and assertIsNotNone"