Trade the dependency on aws-sdk-go for something smaller

[hairyhenderson]

The AWS functions (ec2tag, ec2meta, etc...) add a lot of size to the binary (something like 13MBs, though less when UPX-compressed), can slow things down, and aren't always used...

A whole plugin architecture may be overkill for this project, but some way of lessening the impact would be useful.

Alternatively a much lighter-weight client for the EC2 API calls would help.

[hairyhenderson]

A year later and this honestly hasn't seemed to be too much of a problem... I still think a lighter-weight client would be handy, though.

[hairyhenderson]

Since I logged this, a few things have changed:

• more AWS functionality is being used and added
• the slowdowns have been addressed
• I think most people use the slim binaries (though maybe not all)

I'm going to close this for now. It may be necessary/useful to adopt a plugin system at some point, especially as more and more functions and datasources are added. But it's not time yet...