Switch to using ivy cache in users home directory

One small step for Play, one giant leap back to using SBT in a vanilla
configuration...

* Adds the play local repository to the list of SBT boot repositories,
  so it gets automatically used like it used to when it was instead the
  default local repository.
* Makes the ivy home directory the default one, in the users home
  directory.
* This means ivy cache is shared between vanilla SBT/ivy apps and Play
  apps.
* Also means local repository (when you run publish-local) is shared.
Add imports to form docs
Merge pull request #2060 from jroper/vanilla-sbt

Switch to using ivy cache in users home directory
Extracted some code samples from the Java ToDo Tutorial docs
Replace foreach with map
Merge pull request #2069 from wsargent/patch-3

Replace foreach with map in forms example code
Merge pull request #2062 from gmethvin/form_docs

Add imports to form docs. Fixes #2012.
Merge commit '13cd288dbf7090c9b53ad896545e884643636261'