Add Ability To Create EC2, ELB, and EBS checks.

Can now create checks for EC2, ELB, and EBS checks. Needs more testing
and some tweaking, but it works.
Pull metrics in a series. Slower, but less likely to have rate limiting
issues.
Check for ELB, not EBS (was a typo).
Added RDS support.
Add ability to set AWS Cloudwatch data granularity in config (one minute
or five minutes).
Changed ordering of elements in target.
Changed how broker specification works - brokers are now specified per region,
with a default required in case a region doesn't have any specific broker
associated with it.
Added counts for adding/editing/removing Cloudwatch checks and removed
unused code path ("DELETE" calls).
Store broker tags as well when pulling list of brokers.
Add ability to specify which dimensions you wish to add checks for rather
that just using all available.
Moved Cloudwatch stuff into its own section in Circonus config
to avoid confusion.
Added support for tagging based on broker tags matching AWS tags and
fixed a bug where AWS-specific tags were getting lost.
Translate tags to replace colons in keys with backticks and move tag
translation functionality into its own function.
Added Support For Custom Tag Translations

Added ability for users to define their own custom tag translation
functions and specify which one to use in the config file.
Add ability to specify AWS tag prefix in config file.
Fixed a bug where we were adding too many metrics to certain checks.
Only update checks if something about them has changed.
Remove debug print
Fix some inconsistencies/errors in the data counters and fix a bug
where we wouldn't update a check if the only difference was the brokers
in use.
Tags are always lower case, so make sure we're comparing lower-case
values to other lower-case values when checking for tag equality.