Prepare pantsbuild.pants 0.0.25 release.

Bump the version and add CHANGELOG entries.
Add a script to aid in prepping the CHANGELOG.

Testing Done:
Did a release dry run:
```console
$ ./build-support/bin/release.sh -n
```

Also rendered the CHANGELOG to sanity check - no warnings and looked good:
```console
$ source build-support/pants_dev_deps.venv/bin/activate
(pants_dev_deps.venv) $ rst2html.py src/python/pants/CHANGELOG.rst CHANGELOG.html
(pants_dev_deps.venv) $ open CHANGELOG.html
```

CI went green here: https://travis-ci.org/pantsbuild/pants/builds/44395335

Bugs closed: 874

Reviewed at https://rbcommons.com/s/twitter/r/1496/
Fix the ScroogeGen target selection predicate.

This also updates the release version and CHANGELOG
in anticipation of a quick release.

Testing Done:
Before this fix, reproed the current CI failures with:
```console
$ pants.dev clean-all test examples/::
...
19:52:10 00:20         [compile]
19:52:10 00:20           [jmake]
                         warning: bootstrap class path not set in conjunction with -source 1.6
                         Jmake version 1.3.8-3
                         /home/jsirois/dev/3rdparty/pants/.pants.d/gen/scrooge/java-sync/com/pants/examples/distance/thriftjava/Distance.java:32: error: duplicate class: com.pants.examples.distance.thriftjava.Distance
                         public class Distance implements TBase<Distance, Distance._Fields>, java.io.Serializable, Cloneable {
                                ^
                         /home/jsirois/dev/3rdparty/pants/.pants.d/gen/scrooge/java-sync/com/pants/examples/precipitation/thriftjava/Precipitation.java:32: error: duplicate class: com.pants.examples.precipitation.thriftjava.Precipitation
                         public class Precipitation implements TBase<Precipitation, Precipitation._Fields>, java.io.Serializable, Cloneable {
                                ^
                         Writing project database...  Done.

FAILURE: compilation error
...
$ find .pants.d -type f | xargs grep "package com.pants.examples.distance.thriftjava"
.pants.d/gen/thrift/sessions/examples.src.thrift.com.pants.examples.precipitation.precipitation.thrift/gen-java/com/pants/examples/distance/thriftjava/Distance.java:package com.pants.examples.distance.thriftjava;
.pants.d/gen/thrift/combined/gen-java/com/pants/examples/distance/thriftjava/Distance.java:package com.pants.examples.distance.thriftjava;
.pants.d/gen/scrooge/java-sync/com/pants/examples/distance/thriftjava/Distance.java:package com.pants.examples.distance.thriftjava;
...
```

After the fix the examples run green and:
```console
$ find .pants.d -type f | xargs grep "package com.pants.examples.distance.thriftjava"
.pants.d/gen/thrift/sessions/examples.src.thrift.com.pants.examples.precipitation.precipitation.thrift/gen-java/com/pants/examples/distance/thriftjava/Distance.java:package com.pants.examples.distance.thriftjava;
.pants.d/gen/thrift/combined/gen-java/com/pants/examples/distance/thriftjava/Distance.java:package com.pants.examples.distance.thriftjava;
```

CI went green here: https://travis-ci.org/pantsbuild/pants/builds/44412131

Bugs closed: 875

Reviewed at https://rbcommons.com/s/twitter/r/1497/