The search component receives notifications
when the selected repository changes.
Upon such changes, only display the pages to which
the new filter applies.

Add metadata serach fields for programming language
and keywords of a repository.

Keyword search only works for some words
at the moment, might be an issue with elasticsearch.

Signed-off-by: Lukas Kaltenbrunner <lukas.kaltenbrunner@student.uibk.ac.at>