Add first version of U-Track downloads page
Lowercase u-track across the board
Fix u-track downloads page

- Remove unnecessary top level menu
- Replace Source code by downloads
- Add a get started line
Add link to OMERO downloads page
Yet another nitpick by @hflynn
Merge pull request #63 from sbesson/rebased/develop/utrack

Add first version of u-track downloads page (rebased onto develop)