Expand on @service macro for giving service an alias

[mattBrzezinski]

Stemming from a comment here it would be nice if we could do something like;

@service cloudformation as CF

The problem originates from the AWSTools.jl repo, where there are sub-modules named CloudFormation. This becomes problematic with this package in naming them. As you need to use odd-casings to not have issues. e.g. cloudFormation.

[omus]

Makes sense to use the as syntax which is also used by using/import