Support for filtering request path

[skjolber]

Support for filtering the request path.

Description

Add PathFilter interface (much liker HeaderFilter and QueryFilter).

Motivation and Context

REST services often expose important values directly in their paths. Add support for filtering these.
Fixes #499

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.

[skjolber]

Moved away from the regexp filter - was able to make a simple default filter which should be lightning fast. It accepts path expressions on the form /myApp/orders/{secret}/order, which are commonly found in frameworks like Spring REST (i.e. when using @PathVariable).

[whiskeysierra]

👍