add quoting support to tagging

[Caleb Davis]

Tagging (`#360 </issues/360>`_) needs to be iterated on. This
ticket addresses support for quoting. What are the expected
behaviors? In the following examples, user input is underlined, and
resulting tags are indented.


-  In the simple case (assuming comma-delimited text), the user has
   a single pair of quotes embedded within the input, such as:
   meta,'yo dawg, I heard you like delimiters...',humor

    u'meta'


    u'yo dawg, I heard you like delimiters...'


    u'humor'



-  what about mixed quotes? (eg user wants *you're* in the tag)
   meme,"I don't even...",humor

    u'meme'


    u'I don't even'


    u'humor'



-  then, as Will noted in IRC, some users may wish to tag using xml
   or hierarchical organization schemes. At what point does supporting
   quoting become complex enough to warrant using a plugin?

**tl;dr - introduce support for tag delimiter(s) within a tag. Efforts towards native gmg support go here. Add a new ticket for plugin work**

Feel fix this ticket if I'm missing the point or the point is not
clear.