ZA: Members' interests browser

Creates an interface to browse members' interests data through four different layouts which are displayed depending on the filter specified by the user. Views are a ```complete``` layout (similar to the format published by parliament and displayed on person profiles), a ```section``` layout (allowing comparison of declarations by different people in a single category - e.g. gifts to members of a certain committee), a ```numberbyrepresentative``` layout (total number of declarations in a category per person per year), and a ```numberbysource``` layout (number of declarations in a category attributed to a source per year). Also includes a separate view for searching the sources of data (e.g. sources of gifts).

Also includes an update to test_generation_of_interests_table to address errors caused by the new SAMembersInterestsBrowserTest test case creating data before test_generation_of_interests_table is run.