netbios type should be coerced to integer.

Otherwise the check always fails.
VPCs can now be filtered by id.
VPCs can now be filtered by cider block and dhcp options id
Added the ability to filter vpcs by tags.
allow get_filter_value to return state of ami and test

  * updated Ami.get_filter_value to return the state value of the AMI
  * updated test_ec2.test_amis.test_ami_filters to test for AMIs in the state of 'available'
Test Fixes and `tag:` filter.

  * fixed test_ec2.test_amis.test_ami_filters to test for AMIs in the state of 'available'
  * enhanced AMI's to be able to take `tag:` filter.
  * added tag: tests for AMIs
Merge pull request #214 from thedrow/patch-2

netbios type should be coerced to integer
Merge pull request #219 from joekiller/ami_filter_state

allow get_filter_value to return state of ami and test
Tests will now pass on Python 3.3.
Merge pull request #218 from thedrow/feature/vpc-filters

Added the cider block, dhcp options id and tag filter to the VPC backend
Added the ability to filter by tag-key.
Added the ability to filter by tag-value and refactored the filters to be generic.
Merge branch 'feature/vpc-filters'