Test query search ordre

Test that the order comes out as expected when doing a query
add a first failing unit test for keypairs
return empty key pairs response
add test for create_key_pair
create KeyPairBackend in ec2 model, use in keypair test
implement test for create_key_pair
add test for creating already existing keypair
make duplicate key pair test pass
test DescribeKeyPairs with more than one key pair
implement delete_key_pair, test zero case
test for delete_key_pair
really delete key pair
support names in DescribeKeyPairs
raise NotImplementedError when Filters are used in describe_key_pairs
added support for ScanIndexForward and actual range ordering on range items and not just the dictionaries
tests for reverse query order
Merge pull request #103 from JeffMGreg/master

ScanIndexForward now supported when doing a query
Add support to launch configuration AssociatePublicIpAddress parameter
[tests] Update boto version for the AssociatePublicIpAddress boto fix. Refs #82
Merge pull request #82 from hltbra/associate-public-ip-address

Add support to launch configuration AssociatePublicIpAddress parameter