Fix typos picked up by misspellings

Joe Gordon has introduced a module named misspellings which can check
typo automatically.

$ pip install misspellings
$ git ls-files | grep -v locale | misspellings -f -

Change-Id: I9eca2e097b03468651814fa563e4380fd573205e
ref: http://lists.openstack.org/pipermail/openstack-dev/2013-December/020975.html
Merge "Fix typos picked up by misspellings"