To allow keypair name could contain spaces

To allow the keypair name could contain
letters, numbers, underscores, spaces
and hyphens.

Changes:
Define a new key pair name regex
change key pair Name from CharField to RegexField
modify the test_import_keypair_invalid_key

Closes-Bug:#1288583
Change-Id: I0a20712759359d5cba052f701c51081eee3ca002
Merge "To allow keypair name could contain spaces"