[#307] Fix middleware domain resolution

When running a partner site on a sub-sub-domain like
akvo.localdev.akvoapp.org the construction of request.app_domain
doesn't resolve correctly, the "tertiary" domain gets lost. Fix by
changing how the slicing of the domain parts list is made.
Merge branch 'develop' of github.com:akvo/akvo-rsr into develop
[#307] Fix register link on partner sites sign in page

Also change the password reset link on the same page to use a context
variable to resolve the URL.
[#230]Use focus area image for list meta-tag
Merge branch 'feature/meta-tags' into develop
[#196]Use focus area image for list meta-tag
Merge branch 'feature/meta-tags' of https://github.com/akvo/akvo-rsr into feature/meta-tags
[#230] Add a Facebook share link
Merge branch 'feature/meta-tags' into develop
[#230]Try different style of FB share link
Merge branch 'feature/meta-tags' into develop
[#230] Try FB share btn with own image
Merge branch 'feature/meta-tags' into develop
[#230] change padding and width of like button
Merge branch 'feature/meta-tags' into develop
[#230] adjust padding and remove image border
Merge branch 'feature/meta-tags' into develop
merging from develop
refactoring test steps to remove duplication
moved utility steps from AddProject to world to facilitate reuse