Support single colons

[tancredi]

Hi there,

Thanks for supporting v-* and :* attributes - this is great! Just one question: it seems to only pick up double quotes (E.g. :foo-bar="gettext('bar-foo')" will work but :foo-bar='gettext("bar-foo")' won't) - is there a particular reason for this? Would it be trivial to support?

[nonamenix]

@ykshatroff many thanks )

@tancredi https://pypi.python.org/pypi/babel-vue-extractor/1.4.2