Update sendgrid.markdown

updated node.js documentation
Update sendgrid.markdown

update python example
Update sendgrid.markdown
Update sendgrid.markdown
PHP: $_ENV to getenv
Merge branch 'UpdateSendgridDocumentation' of github.com:laur-craciun/afdocs into UpdateSendgridDocumentation-20140120
updated AppFog documentation to use the last library for node.js/python
updated subject
Merge branch 'master' of github.com:vladiacobsendgrid/afdocs into UpdateSendgridDocumentation-20140120
Merge pull request #38 from laur-craciun/UpdateSendgridDocumentation-20140120

Update SendGrid documentation