Support issuer name in URI generation

[jamesob]

In the Google Authenticator app, if the URI specified doesn't include an issuer_name parameter, the Authenticator entry will lack a title.

This PR brings URI generation in pyotp closer into compliance with Authenticator's key URI format.

[nathforge]

Thanks for this, looking good - I'd only say that utils.build_uri() should run
issuer_name through urllib.quote, and to change from . import utils to
from pyotp import utils, so we don't break older versions of Python.

[jamesob]

@nathforge good calls. Updated.

[kislyuk]

👍 I've been adding the title manually, nice to have it in the library.

[jamesob]

this guy ready to go in? anything else to take care of, @nathforge?

[nathforge]

Nope, just hadn't run tests. All good, thanks James!

[nathforge]

1.4.1 uploaded to PyPI