Merge pull request #1 from mzimmerman/master

added ability to this library under AppEngine by passing in an appengine...
Added better error reporting for Send method
Merge branch 'master' of github.com:elbuo8/sendgrid-go
Multiple changes see comments

1. Web API now uses POST instead of GET
2. Added partial support for file uploads (Web only for now)
Added header support
Not doing regex anymore
Up to date README file
Left logging messages :(
Added simple unittest
Updated readme
More comprehensive mail
Better README page
Added BCC support
Added some more info
Moved the files to the root domain
Better docs
Use api.sendgrid.com
Added SMTP test, file attachment limit and support for SMTP
Working version of smtp with file attachments. Aleluya!
Refactored code and working x-smtp headers