Re-factored test project import code.

Added new `ProjectImporter` class which extracts test project import
code from the problematic super-class `AndroidMavenPluginTestCase` and to
replace the method `importAndroidProject` in future releases.

This new class uses a fluent builder design pattern to make tests more
expressive and to make it easier to re-factor the complex,
`importProject` method in future.
Fixed bad output location on project folder/name mismatch.

Fixed bug causing output location to be incorrectly set to `bin/classes`
ADT default for main source folders if the project workspace folder and
name do not match:

http://github.com/rgladwell/m2e-android/issues/issue/213

Added tests to verify that the main source folder output location is
correctly set when the project name and project folder do not match.
Tidied Maven Eclipse classpath translation code.

Re-factored code to translate the Maven Eclipse classpath: this is now
simpler,