Adds keypair create,delete integration tests

I have added test_keypair.py which tests create keypair and delete
keypair methods. And to allow this I have added keypairpage.py with
two methods to create and delete keypairs. I have added
accesssecuritypage.py which has_click_on_keypair_link method.

Partially implements blueprint: selenium-integration-testing

Change-Id: I9f8680fb51aa7dcf249e7487efa46240200a0ef2
Exception handling is captured correctly when deleting a container.

When deleting a container that is not empty, the exception code
does not send the error message through exception.handle. Instead,
it raises an exception which causes an error when Horizon is no
longer in debug mode.

Change-Id: Iee8601c5b0f831b2dd598accfdc58cb8130cca13
Closes-bug: 1355405
rename pagination 'More' link to 'Next'

The term 'More' is not standard and suggests appending more items
to the existing table rather than going to the next set of data.

Change-Id: I47f06f43e60012f502e70817feccf458fca7eef2
Closes-Bug: #1323880
Merge "Adds keypair create,delete integration tests"
Merge "rename pagination 'More' link to 'Next'"
Merge "Exception handling is captured correctly when deleting a container."