Update most deps required for Play 2.1-RC2 and Scala 2.10

Note this does not actually pass tests, and  no
"org.mongodb" %% "casbah-core" % "2.5.0" yet - but it's coming:

https://groups.google.com/d/topic/mongodb-casbah-users/Tiy9r2SMPcQ/discussion
Fix the awful case of the mysteriouslye missing JTA

http://teamcity.gudev.gnl:8111/viewLog.html?buildId=68043&buildTypeId=bt185&tab=buildLog

[14:07:10][info] downloading http://repo1.maven.org/maven2/com/github/scala-incubator/io/scala-io-core_2.10/0.4.1/scala-io-core_2.10-0.4.1.jar ...
[14:07:24][info] 	[SUCCESSFUL ] com.github.scala-incubator.io#scala-io-core_2.10;0.4.1!scala-io-core_2.10.jar (14096ms)
[14:07:24][info] downloading http://repo1.maven.org/maven2/com/jsuereth/scala-arm_2.10/1.2/scala-arm_2.10-1.2.jar ...
[14:07:26][info] 	[SUCCESSFUL ] com.jsuereth#scala-arm_2.10;1.2!scala-arm_2.10.jar (1480ms)
[14:07:26][warn] 	[NOT FOUND  ] javax.transaction#jta;1.0.1B!jta.jar (0ms)
[14:07:26][warn] ==== public: tried
[14:07:26][warn]   http://repo1.maven.org/maven2/javax/transaction/jta/1.0.1B/jta-1.0.1B.jar
[14:07:26][info] downloading http://repo1.maven.org/maven2/org/scalatest/scalatest_2.10/1.9.1/scalatest_2.10-1.9.1.jar ...
[14:07:26][info] 	[SUCCESSFUL ] org.scalatest#scalatest_2.10;1.9.1!scalatest_2.10.jar (97ms)
[14:07:26][info] downloading http://repo1.maven.org/maven2/org/mockito/mockito-core/1.9.5/mockito-core-1.9.5.jar ...
[14:07:34][info] 	[SUCCESSFUL ] org.mockito#mockito-core;1.9.5!mockito-core.jar (8293ms)
[14:07:34][warn] 	::::::::::::::::::::::::::::::::::::::::::::::
[14:07:34][warn] 	::              FAILED DOWNLOADS            ::
[14:07:34][warn] 	:: ^ see resolution messages for details  ^ ::
[14:07:34][warn] 	::::::::::::::::::::::::::::::::::::::::::::::
[14:07:34][warn] 	:: javax.transaction#jta;1.0.1B!jta.jar
[14:07:34][warn] 	::::::::::::::::::::::::::::::::::::::::::::::
[14:07:34]sbt.ResolveException: download failed: javax.transaction#jta;1.0.1B!jta.jar

https://github.com/jsuereth/scala-arm/pull/21
Update Play request metrics for Play 2.1

Now using filters, and a bit more sane - the required configuration
is much more concise.

With a couple of tests too!
Merge pull request #21 from guardian/play-2.1

Play 2.1 support (with Request metrics that work!)