Add timezone of build timestamp (#439).
Revised documents for version 0.7.0 (#420).

* Revised for supporting Hadoop2 as generally available.
* Revised deployment guide with profile of Gradle Plugin.
Refactoring (#421).

* Add package-info.java.
* refactor DataInput.readUTF/DataOutput.writeUTF.
* reduce some obsoleted task tags.
Regression: Tester#skipXXX performs inverse (#437).

* Fix and introduce skipValidateCondition().
Modified TestEnvironment w/o configuration (#438).

* OperatorTestEnvironment now permits missing asakusa-resources.xml.
Merge remote-tracking branch 'private/issue/420-M28' into 0.7-develop
Merge remote-tracking branch 'private/issue/421-M28' into 0.7-develop
Merge remote-tracking branch 'private/issue/437' into 0.7-develop
Merge remote-tracking branch 'private/issue/438' into 0.7-develop
Merge remote-tracking branch 'private/issue/439' into 0.7-develop
Merge remote-tracking branch 'central/0.7-develop' into 0.7-release
Bumped version number to 0.7.0-RC2