Enforce usage of maven 3

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
Fix dml-maven-plugin's support for tests

  * Correctly copy dml resource to test-classes
  * Correctly set the classpath in augmentClassLoader
Add test module, containing test-txintrospector submodule with tests for txintrospector

  * Tests in the test module are separate from other modules because the they
    need a full fenix framework stack to work.
  * All tests run successfully against the current txintrospector version.

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
Add a simple eclipse m2e lifecycle mapping for dml-maven-plugin that ignores goals from the plugin
Splits the responsibility of shutting down the FF to the Config and backends
Add hibernate-search module, that supports the indexing of domainobjects using hibernate-search

  * This module is responsible for using TxIntrospector to automatically index
    new and modified instances of classes marked with @Indexed during a
    transaction (and their relations).
  * User code can perform queries by using the SearchFactoryImplementor
    instance that can be obtained by calling
    HibernateSearchSupport.getSearchFactory().
  * The functionality from this module is only enabled at run-time if a
    configuration file for hibernate-search was provided.

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
BUGFIX: Only close EntityManager after committing
BUGFIX: Don't call toString() on DomainObjects in TxStats.toString()

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
BUGFIX: Ensure the DomainRoot is always used inside an @Atomic block in test-txintrospector

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
Fix pom.xml so that test-txintrospector can also successfully execute with the ogm backend

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
Revert accidental change to ogm backend
Add test-hibernate-search module, containing tests for the hibernate-search module

  * All tests run successfully against the current hibernate-search version
    (when run with the infinispan backend).

Work done in collaboration with Hugo Rito <hugo.rito@ist.utl.pt>
Switch hibernate-search to being implicitly enabled/disabled if the config file is provided
BUGFIX: Correctly detect maven.test.skip property in dml-maven-plugin

  * Add this check to the TestDmlPostProcessorMojo.  It was failing when
    looking up the project.properties supposedly generated by
    TestDmlPostProcessorMojo, because the latter was already complying with
    this property.
Harmonize configuration (Hibernate-search and DAP)

  * Apply the configuration by convention principle to DAP. The config file is
    always 'dap.properties'.  No longer need to set the name of the config
    file in fenix-framework-<backend_here>.properties file.

  * Homogenize logging between hibernate-search and DAP modules
Define a constant to enable TxIntrospector

  * Update code to use the constant instead

  * Move TxIntrospector constants from TxStats to TxIntrospector as supposed
Module Hibernate-Search now ensures at boot that required module TxIntrospector is on
Make DAP_ENABLED a constant in its code generator
Extent README.md with reference to modules, esp. DAP
Fix typo in previous commit :-(