Allow capturing a postfix "rest of path" as route parameter

[robinei]

Allows the following syntax for route strings:
"/users/:userid/files/::path"

A ::-prefixed name may be supplied last in the string, and in the
example above this allows matching on strings like this:
"/users/123/files/Pictures/Summer2012"
where userid="123" and path="Pictures/Summer1012"
or
"/users/123/files/"
where userid="123" and path="".
(so unlike other parameters, this one can be empty)

[lhorie]

This is a nice feature to have, but I have a few reservations:

• double colon is not a super intuitive syntax (elsewhere double colon is usually the syntax for namespace resolution). It's also easy to create unintentional bugs due to typos, and it's easy to mistake it for a typo if one doesn't know what it is
• the argument doesn't bind to the value correctly if used in a route like /foo/::id/bar

I added support for this and added a fix for the second point, but I'm proposing a slightly different syntax (/foo/:id..., /foo/:id.../bar) which is similar to variadic function syntax from C++, Java, etc. Documentation and tests have also been updated

The work above is done in origin/next and scheduled to be released in v0.1.12

[robinei]

This looks good :)