PYCBC-41, PYCBC-27: Better view option handling

The behavior is largely followed from php-ext except with the decision
to implement the validation bits in pure Python rather than C

This does *BREAK* existing behavior of the _view() function which now
smartly tries to convert values to JSON when needed

Change-Id: I16c143d652e5936eda26fe0c0ea13e14a9c29be5
Reviewed-on: http://review.couchbase.org/26608
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>