Add prepend capabilities to the queue.

Add a new 'prepend' task type.
Add new append and prepend tasks.

append is just an alias of load, provided for consistence with prepend.
Add a new task "readBefore".

This task if the file version of the "prepend" task for strings.
Merge branch 'master' of https://github.com/fpirsch/gear
minor changes to new prepend task type pull request