Created email object class
Moved all email information to Email class
Updated Readme
Refactor. Changed every 'password' to 'key'
small refactor
removed xsmtp header
changed class email to SendGridEmail
added support for the SMTPAPI lib
added setTos method to SendGridEmail
updated README
Merge pull request #6 from heitortsergent/master

Updated lib to be more similar with other languages