Url alias on content edit form does not support tokens

Problem/Motivation

Url alias rules can use tokens; however, if during the content edit process you want to override the token for a particular item you cannot. This seems like a mismatch in functionality. Our menu alias structure depends on the use of [node:menu-link:parents:join-path]/ and without it content will not display correctly but I can imagine a lot of scenarios where a one rule per content type won't match business.

Steps to reproduce

* enable path alias for content types
* go to node/add/page
* add [node:title] to Url alias field and save
* note that token is escaped.

Proposed resolution

* update widget with "supports tokens" text
* add service to replace token with text.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet