Create util functions from templatetags code

[michaeljones]

As briefly discussed in #95.

From the commit message:

Rather than doing the work in the template tags, we do the work in utils
functions so that the same functionality is available directly to Python
application code.

This can be useful for media properties on Django widgets (#95).

The README has been updated to provide simple examples of usage.

It feels a bit weird to mostly cut & paste code between the files but it seems that that is most of what is needed. I'm not sure that the get_as_tags function is exactly necessary but it seemed like it might save someone some trouble if they wanted to achieve similar results.

Very happy to change any and all of it. Especially the names of functions. Naming is hard :)

I've attempted to provide a bit of README and doc strings but they could be better I image.

I've run the tests locally and everything seems to pass. I confess I haven't looked at it closer than that though.

Thanks again,
Michael

[coveralls]

Coverage decreased (-0.5%) to 96.835% when pulling 24ea47f on michaeljones:utils into c858d50 on owais:master.

[owais]

Restated the CI build. Will approve if it passes but please take a look if it fails again.

Thanks for the PR

[coveralls]

Coverage increased (+0.1%) to 97.436% when pulling 2f4fb2e on michaeljones:utils into c858d50 on owais:master.

[michaeljones]

The attrs=None part of get_as_tags wasn't being covered but I realise the template tag assumes attrs='' so I've change get_as_tags to have the same approach which restore the coverage totals.

[ntucker]

Please release a version to pypi with this. So incredibly useful!!!

[ntucker]

Hmm, tried just installing the git hash and got

IOError: [Errno 2] No such file or directory: 'README.rst'

[owais]

I don't I'll have time to release this to pypi or fix direct git install or the next 2-3 days. PRs to fix git install welcome!

I'll release a version to some time later this week.

[ntucker]

Ok, I created #97. :)

[pacahon]

@owais Hello! Looks like release on pypi still outdated. Do you have some time to fix this? Thanks.

[owais]

@pacahon I released a version to pypi yesterday. Could you check if it works for you now?

[pacahon]

@owais Thanks! I can install 0.4.1 only with pypi right now (no updates on site too) Will check it again tomorrow and write the results.

[pacahon]

Of course, i forgot to respond. It's ok since yesterday. Thanks again.