Permalinks, history and overall improvements

This PR solves #4 completely and solves #18 for all pages excepts the "validate" and "extract" pages, which I will work on later.

Changes made:

All pages in the client application can generate permalinks (included the SPARQL query endpoint).
The server is now capable of generating short permalinks (see https://github.com/weso/rdfshape/pull/118), so the WIkiShape permalinks are now shorter than before.
Permalink buttons are located in more visible places and clicking on them copies the permalink to the clipboard.
Pressing back on the browser will return to the previous validation/operation/query instead of returning to the last page.
Bug fixing, code refactoring and styling

weso / wikishape