[split] Fix Travis CI config and add missing dependency to SBT build

Problem

We're no longer cross-building against 2.9.2, but that's what's in the Travis
configuration. The SBT build is also missing the ScalaCheck dependency.

Solution

Update the version, add the dependency.

Result

Tests run as expected on Travis.

RB_ID=484635
[split] util-logging: factor out testing code into new package util-test

Problem

util-logging exported a dependency on scalatest. This causes broken
builds when used in Science, which is still on Scalatest 1.x.

Solution

Factor this out into its own package, and use selectively.

before% ./pants goal dependencies twitter-server/src/main/scala | grep scalatest
3rdparty:scalatest
org.scalatest:scalatest_2.10:2.2.2
before%

after% ./pants goal dependencies twitter-server/src/main/scala | grep scalatest
after%

RB_ID=482011
[split] Strip Dtab headers from Http requests before adding Dtab.local to request headers

Problem:

Finagle encodes Dtab.local into request headers. However, it's possible, for instance if a request object is accidentally reused, to add many Dtabs to a request.

Solution:

Ensure that a request is stripped of Dtab headers before appending Dtab.local to Http requests.

RB_ID=478527
Merge branch 'tmp' into develop