add -kanal as seperable street suffix

[missinglink]

highlighted in pelias/pelias#854 the parser was not familiar with Am Nordkanal being a valid street name.
I've added -kanal to the list of German suffixes commonly found in street names.

closes pelias/pelias#854

[msschl]

-allee e.g. Königsallee in Düsseldorf
-platz e.g. Rathausplatz
-weg e.g. Plutoweg
-strasse e.g. Dorfstrasse

[Joxit]

LGTM

[Joxit]

You can add tests for Königsallee and Plutoweg.
They are already working but not in our tests.

[missinglink]

@msschl the other cases you provided already seem to work fine, I added some test cases anyway in 662ed6f