Project search and other fixes

**Make sure you run migrations and re-start your server**

**Summary:**

1) Set a project search through: 
  - *Filters:* name, fields of study, student passions, team mode and session timeframe. 
  - *Sort:* A-Z, Recent, Oldest.
  - *Explore by:* Grid and List views.

2) Connect home search to project search
3) Fix primary and secondary menus
4) Remove search bar from drop down menus in Footer "Contact Us" section
5) Integrate homepage with Refinery, so images and text is editable somewhere in the interface. *(WIP: Styles need to be fixed)* 
6) Add ability to remove bottom margin from images in Refinery Page Parts
7) Set the student passions filter as checkboxes

**To do:**
  - Specs for projects (acceptance).
  - Styles for ransack helpers, normal helpers are used.
  - Set refinery homepage as homepage

**Issues:**
  - There's some kind of problem saving individual and public projects (team_mode: false, location_private: false).
  - Also a project can't be save if the initials of the users are register. Throws some pg error
  - Since *region* field is missing the filter is not defined yet.
  - Also since dates are handle in the *ProjectSession* model (which is currently located in another [branch] (https://github.com/ipoconnection/ipo-web/blob/dev/app/models/project_session.rb#L2)), the 'Session Timeframe' filter is temporarily working with *created_at* field. 
  - Register a new project, go to another page (p.e homepage), returns to the project form, it shows the last project recorded, so there's no easy way to register a new project