Merge branch 'release/0.1.0' into develop
extract the `is_internal` test and supply its docs.
extract the `is_current` test and supply related docs.
remove the useless processing for external url.

Thanks for the review of @shonenada .
Merge branch 'feature/refine-is-active' into develop
add optional paramater to contain html attrs.
add utility to make dict into html attrs.
add html representation feature for item.
add format_spec support. Close #3
test the extra html attributes. Close #7
supply docs for pre-defined html attributes usage.
fix up the docs.
Merge branch 'feature/html-attrs' into develop
enable the python 3.4 on travis ci.
revert docs/Makefile
pick krTheme from PyPI.
install project as dependency.
Merge branch 'feature/refine-docs' into develop
Added nested items
Added nested items documentation