Ignore .coverage* files

When a coverage command aborts, some temporary files related to the
coverage remain like this:
    .coverage.localhost.24409.990268
    .coverage.localhost.24415.503858
    .coverage.localhost.24417.953422
    .coverage.localhost.24419.169526
    .coverage.localhost.24421.143443
    .coverage.localhost.24423.259249
    .coverage.localhost.24425.429360
    .coverage.localhost.24427.025521
    .coverage.localhost.24432.204681
    .coverage.localhost.24479.725555
We should not manage these files in the git repository.

Partially implements bp unit-tests

Change-Id: Ifa5aaa526b27473c5e5220a5be4a910603676e60
Stop test server leaking even if an error happens

Some api/compute test creates multiple test-servers in setUpClass(). But
if an error happens, some servers are not deleted because
tearDownClass() is not called.
This commit fixes it.

Partially Implements: blueprint stop-leaking

Change-Id: I448bf844a19cd88da0dd3a6da162711307e34b30
Merge "Stop test server leaking even if an error happens"
Merge "Ignore .coverage* files"