Version 1.8.0

This is the last version that supports Python 2.

Some new features in this version:

• A better way to pass table action URLs (#146, #151)
• Some configurations to change table action titles (#140)
• SRI support (#142)

See the changelog for details: https://github.com/greyli/bootstrap-flask/blob/master/CHANGES.rst#180

Thanks to @yuxiaoy1 and @caffeinatedMike!