Strip out Traceback from HTTP response

We should not let stack traces leak to the REST API users

Fixes LP# 1103324
Fixes LP# 1092610

Change-Id: Ic1208bfeb7d44e672f8b8d3a4004a9802c14e7b9
Avoid hard dependency on python-coverage.

Updates the coverage extension in the OpenStack Compute API to
avoid a hard dependency on the python coverage module. We now
try to import 'coverage' and if it isn't present we return
an HTTP 503 (service unavailable error).

This gets rid of WARNING errors which occur when running Nova API
when the 'coverage' module is not available:

2013-01-27 17:10:28.938 16018 WARNING nova.api.openstack.compute.contrib
[-] Failed to load extension
nova.api.openstack.compute.contrib.coverage_ext.Coverage_ext: No module
named coverage

Fixes LP Bug #1101057.

Change-Id: I573180aead44d68b8377cd66f30fc6ac849d0272
Allow users to specify a tmp location via config

Fixes bug 981104

Although the temporary directory used can be controlled via
environment variables, this patch provides a way to define it
explicitly via a config option.

The default value is None, which behaves per the doc below:
http://docs.python.org/2/library/tempfile.html#tempfile.tempdir

Flags: DocImpact
Change-Id: I47b6d8bac734f453c80d541b46086a30e847c859
Fix a typo of log message in _poll_unconfirmed_resizes

That is just a negligible typo issue, so I have not filed a bug on LP.
The typo log message is like "notRESIZED/None", and should be
"not RESIZED/None".

Change-Id: I6137b477185419b1e638be3ed5310644aff96d76
Merge "Avoid hard dependency on python-coverage."
Merge "Fix a typo of log message in _poll_unconfirmed_resizes"
Merge "Strip out Traceback from HTTP response"
Merge "Allow users to specify a tmp location via config"