Add SPF to supported record types of the Rackspace DNS driver.
Modify Rackspace DNS driver to set record name to None for the records
which correspond to the root domain.

This is done for consistency with other drivers.
Update Zerigo DNS driver to set Record.name attribute for records for bare
domains to None instead of an empty string.
Update .gitignore.
Update CHANGES.
Update upgrade notes.
Adding/Removing instances from targetpool requires a list. This fixes a bug with attaching/detaching nodes from loadbalancers. (Attach/Detach wasn't working)

Closes #228.

Signed-off-by: Tomaz Muraus <tomaz@apache.org>
Update CHANGES.
Handle Rackspace pagination of DNS records.

Rackspace paginates DNS records returned from their API. In list_records, query
Rackspace multiple times, if needed, to get the full list of records.
Move paginated DNS query code to iterate_records.
Remove unused variable.

Fix lint warning.
Merge branch 'trunk' of github.com:briancurtin/libcloud into trunk