Ignore resource directories when trying to loadMessages in MessagesPlugin, otherwise app don't start if there's a matching directory
remove unnecessary exec ctx prep from Iteratee.flatMap

commit 2b276d24 implemented the lines:
```
case Step.Done(a, Input.Empty) => executeIteratee(f(a))(ec /* still on same thread; let executeIteratee do preparation */ )
case Step.Done(a, e) => executeIteratee(f(a))(ec.prepare /* still on same thread; let executeIteratee do preparation */ ).pureFlatFold {
```
However, the `ec.prepare` is incongruous with the adjacent comment, and the preparation is definitely not required as the preparation is indeed handled by `executeIteratee`.
Fixed async code links

Changed async code links from being relative links with parent traversal
to being absolute links so they'll work with the git repo on
playframework.com.
Merge pull request #2109 from orrsella/messages-fix

Having a "messages/" directory under resources throws exception during startup, fails app
Make ehcache config resource configurable
Fixed a bug in documentation comments
Doc: Add instructions to config override

First add an example of command line overrides, also describe how to make it work for tests.
Upgrade to Guava 16.0.1 to fix JDK and Guava TypeVariable compatibility: https://code.google.com/p/guava-libraries/issues/detail?id=1635
Consume all enumerators created by gzip filter

This fixes an issue with New Relic monitoring and GzipFilter.
The New Relic monitoring tracks all promises to completion,
and an unused empty enumerator caused problems with this.
Merge pull request #2353 from gmethvin/ehcache

Make ehcache config resource configurable
Merge pull request #2360 from platy/patch-2

Doc: Add instructions to config override
Merge pull request #2356 from deniskr/patch-1

Fixed a bug in documentation comments
Merge pull request #2361 from benmccann/guava-upgrade-16_0_1

Upgrade to Guava 16.0.1 to fix JDK and Guava TypeVariable compatibility
Merge pull request #2362 from pvlugter/gzip-filter-enumerators

Consume all enumerators created by gzip filter
Merge pull request #2257 from dwhjames/topic/iteratee-ec-prepare

Remove unnecessary execution context preparation from flatMap on iteratees