Make it possible to disable extension for a particular URL pattern

[comonadd]

I'm opening this issue because:

• I'll report a bug
• I'll propose a new feature

Description

It is sometimes needed to disable the extension on a particular set of web-applications. This option should be present in the configuration of the extension.

The user should be able to enter a list of regular expressions, and, the extension would be disabled on the web-pages, URL of which matches at least one of the specified patterns.

[lukeallister]

I agree, this would be a great enhancement. I currently have to manually disable it when I want to navigate certain sites.

[ueokande]

duplicated in #11. Please discuss in that PR.