Dr hiring emails

The on-demand hiring emails should be working now! To make it easier to review this branch, I pushed it to a dev heroku since it involves testing the email feature (which is annoying to do in local host). Therefore, review this branch at the following url: http://foundry-app-dev.herokuapp.com/

To review it: 

1) Register on foundry (or use my account -- username is "daniela")
2) Create a new team and add a few tasks 
3) Click on a the "hire" button on one of the task modal, which should take you to a new page with the hiring emails 
4) Try sending each of the three email types (which you can see in the sidebar): task available, task acceptance and task unavailable. Make sure that the information in the forms and emails are correct. By default, the forms should pull in the task information from the foundry workflow but you are welcome to edit the information via the form and that updated information will be sent in the email (but it will not update in foundry or in subsequent emails).

A few other things: 
- Make sure the links on the sidebar (especially those to the other tasks) are correct (i.e. they link to where they should link to)
- Make sure you receive the emails (you should be able to send to multiple emails at once)
- Several of the input fields in the form are "required" 
- For the "Your Email" field, if that is empty, it will send from stanfordhci.odesk@gmail.com
- The design (especially of the sidebar) still needs work but I wanted to get this working first

Feel free to keep a list of design details we should fix (that can be done in a separate branch once this one is merged).