Fix typographical error(s)

[orthographic-pedant]

@mgonto, I've corrected a typographical error in the documentation of the restangular project. Specifically, I've changed cannonical to canonical. You should be able to merge this pull request automatically. However, if this was intentional or if you enjoy living in linguistic squalor, please let me know and create an issue on my home repository.

[pedromarce]

What do you think about this @ConcurrentHashMap? Maybe create an alias to keep cannonical (backwards compatibility) and add proper canonical methods updating readme? Or just ignore it?

[bostrom]

Perhaps add canonical an alias, deprecate (with warning) the use of cannonical and remove it (with breaking change notice) in the next major release?