Escape % in db+table names before adding to a format string being passed into db.execute()

Fixes #416
Misc EC2 doc tweaks.
More EC2 doc tweaks
Remove potentially out of date or specific product references.
Split out route table and subnet functionality from VPC module.
EC2 subnet/route-table: Simplify tag updating.
ec2_vpc - Formatting updates.
ec2_vpc - VPCException -> AnsibleVPCException
ec2_vpc - Fail module using fail_json on boto import failure.
ec2_vpc_subnet - resource_tags is not required.
ec2_vpc - More efficient tag search.
ec2_vpc - Implement vpc_name parameter.
ec2_vpc - Update some documentation strings.
ec2_vpc - Update dict comprehensions and {} formats for python2.6
ec2_vpc - More dry running in check mode.
ec2_vpc_route_table - Support route propagation through VGW.