Remove all empty path parts from the parsed url.

Trim only removes empty binaries at the end
Eg: elli_http:parse_path({abs_path, <<"//map//stuff.json">>})
now: {ok, {..., [<<"map">>,<<"stuff.json">>], ...}}.
previously: {ok, {..., [<<>>, <<"map">>,<<>>,<<"stuff.json">>], ...}}.

We could remove the first clause or split_path/1, and then make the list comprehension in split_path. What do you think?