Adding global option to strip out pagination string from canonical URLs.

Hi Bjorn,
I know we're discussing this in another issue, but I had some spare time tonight and thought you might appreciate the help :)

I've just added in a global option for stripping out the pagination strings from the canonical URLs. You can see what I've done here. Pretty basic stuff.

I've tested this out in EE 2.8.1 and it works fine. A URL i.e. "/about-us/media/P10" results in a canonical URL of "/about-us/media/" if "Include pagination links (i.e. P10) in canonical URL output?" is set to "No".

The only thing I'm missing is a french translation for the main control panel label I don't speak French :(

Thanks again for the plugin Bjorn.