Initial support for network acls
get_all_network_acls now works properly
Removed extraneous comments.
Added support for associating and disassociating network ACLs and
subnets.
Added supoprt for replacing network acl entries.
Now properly populates NetworkAclEntry class with icmp & port range
options.
Removed unnecessary import of NetworkAclEntry.
fix for proxy user with dots or hyphens
fix for os.env proxy without port
added some tests for connections behind proxies
Update elastic transcoder docs
Add release notes for 2.15.0
Merge branch 'transcoder' into retry
Version bump to 2.15.0
Added launch_config's parameter associate_ip_address for VPC
Adding recipe for parallel execution of activities to SWF tutorial.
Support for instance tenancy in create_vpc
Add DHCP options filtering
Merge pull request #1800 from oozie/swf_tut

Adding recipe for parallel execution of activities to SWF tutorial. Fixes #1800.
Unit tests for create_vpc and get_all_dhcp_options
Convert existing VPC tests to AWSMockServiceTestCase, typos