Add pluggable job executors for TestDriver (#358).
Fix #357.

Fix on loading empty files as JSON for testings (#357).
Merge remote-tracking branch 'private/issue/357' into 0.6-develop
Merge remote-tracking branch 'private/issue/358' into 0.6-develop
Fix on searching jobflow package on testing (#358).
Fix regression (#358).

If Hadoop configuration location must be inferred
from the current environment.
Fixed #359.

Direct I/O does not detect data source correctly when using base path
with valuables.
Fixed #360.

TestDriver fails on project with blank space path.
Fixed #361.

Add TestDriver API for preparing and verifying test data with model
object collection.
Fixed #362.

TestDriverBase#setFrameworkHomePath does not work.
Merge remote-tracking branch 'private/issue/359' into 0.6-develop
Merge remote-tracking branch 'private/issue/360' into 0.6-develop
Merge remote-tracking branch 'private/issue/361' into 0.6-develop
Merge remote-tracking branch 'private/issue/362' into 0.6-develop

Conflicts:
	testing-project/asakusa-test-driver/src/main/java/com/asakusafw/testdriver/TestDriverContext.java
Add document for #361 (#346).
0.6.0 Refactoring (#363).
Merge remote-tracking branch 'private/issue/346-M5' into 0.6-develop
Merge remote-tracking branch 'private/issue/363' into 0.6-develop
Add TestingEnvironmentConfigurator (#364).

To configure the testing environment, implement
"TestingEnvironmentConfigurator" class and put
the implementation class name in
"META-INF/services/com.asakusafw.testdriver.core.TestingEnvironmentConfigurator".

Clients can suppress this feature with setting
"-Dasakusa.testdriver.configurator=false".
Merge remote-tracking branch 'private/issue/364' into 0.6-develop