Adding History-related grunt tasks

This is a set of history related tasks that Dav asked to be added to grunt-yui-contrib.

**history-rollup**, Creates History Rollup file (Run before history-replace)
**history-populate**, Populates History files with @VERSION@ if not there already 
(actually adds the whole entry e.g.
```
@VERSION@
------

* No changes.
```
)

**history-replace**, Replaces @VERSION@ in History files with *release-version*