Added to the provisioning_uri method in HOTP and TOTP classes the
ability to call the util's function build_uri with all the necessary
arguments.

Added to the function build_uri the ability to handle values different
than the defaults for algorithm, digits and period when generating URI.

Made some corrections to pass the standard PEP-008 in all files.
Corrected lint errors in docstring in utils' function build_uri. Also
corrected an import error for python 2.x and indentation error in utils
module.

Added the corresponding tests for the new URI generated parameters for
both, HOTP and TOTP algorithms. Some earlier tests had to be reformed
because now the URI parameters are encoded using urlencode instead of
concatenating strings. The string generated by urlencode comes from a
dictionary and dictionary items do not have a predefined order.

Also corrected some PEP-008 issues.