EC2 Instance metadata split into groups for caching - EUCA-5762

Generation of EC2 instance metadata is now split into groups to avoid
generating expensive data when not requested. The IAM metadata is now
cached for five minutes and other metadata groups are not cached.

EUCA-5762
NioHttpDecoder now uses exhaust logger - EUCA-6020

The exhaust log is now used instead of a Jetty Logger so extremely
verbose low level output is usually suppressed.

EUCA-6020
Bouncy castle provider installed with higher priority - EUCA-5833

The bouncy castle security provider is now installed with higher
priority so it is used instead of the default implementation.

The previous change to disable DHE ciphers is reverted.

EUCA-5833
Merge remote-tracking branch 'origin/dev/sjones/EUCA-5833_bc' into testing
Merge remote-tracking branch 'origin/dev/sjones/EUCA-6020' into testing
Merge remote-tracking branch 'origin/dev/sjones/EUCA-5762_mg' into testing