Fix breadcrumbs, and reduce template code

This pull request does two things: 

1. Rename 'Search' in the breadcrumbs to 'Home'. This fixes https://github.com/18F/foia-hub/issues/243

2. Both profile.html and parent_profile.html had a lot of common template code. That's been reduced into one file, and used through includes. This means we only have to make changes in one place. 

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