Fix persistence configuration

Use the right version in persistence.xml, remove unnecesary class tags, change some property names for the javax.persistence equivalents and add the MySQL dialect.

Remove the mysql-connector-java dependency. Now is necessary to place the corresponding jar file in the lib folder of Tomcat. Also remove some javax.sql and jta unnecessary dependencies.
Fix oneToMany association between User and Program

There was a foreign key from PROGRAM.ID_PROGRAM to USER_.ID_USER_ and no join table.
Setup test DB using H2

Add the H2 dependency.
Use an in-memory H2 database.
Move the properties file to a better location and modify the path Config.
Add a persistence.xml file for testing.
Declare explicitly the entity classes in both persistence.xml files because of problems with H2.
Create a dummy test case for UsersFacade.
Add an initialization SQL script for H2.
Create test for the activateUser method in UsersFacade.

Fix the missing assignment of the active field of UserVo in UserEntity.toVo().
Adopt naming conventions for test methods in UsersFacadeIT.
Implement test case BL-10.2 on UsersFacade.

Test of an invalid confirmation key.
Implement test case BL-3.1 on UsersFacade.

Test of an successful login.
Implement test case BL-3.2 on UsersFacade.

Test of an invalid login.
Implement test case BL-3.3 on UsersFacade.

Test of a login attempt with an inactive account.
Beginning of test cas BL-1.1
Fixed the Relations Between UseEntity - ConfirmationKeyEntity and UserEntity - ProgramEntity; Added Unique constraint for PeriodEntity in the pair of fields Year and Semester
Finished test case BL-1.1. Some changes where made for it to pass. Changed Travis configuration for running IT tests.

 * The getPersistenceUnit in Config now returns the EntityManagerFactory for the application (the same that the FacadesFactory uses)
 * The search method in CourseFacade now is not case sensitive.
 * Fixed some mistakes around the code of ratings (some Queries) and professors, so the facade would work with no problem.
 * Added more data to the init.sql database, to be prepared for CommentsFacade Tests.
Finished test case BL-6.1.
  * Fixed a simple bug in constructing the name of the professor.
Finished test case BL-1.2
Finished test cases BL-1.3, BL-6.2 and BL-6.3. Improved test case BL-1.1.
 * Fixed getById method in SimpleCrudService to return null when necessary
Begin test BL-4.1
Merge of saaperezru-testing with dao-refactoring
Merge of trunk with saaperezru-testing and dao-refactoring
Merge with dagerenaq-DataBaseChange. All tests from Courses and Users are working.

 * Modified the init.sql to support changes in the dabtase for ConfirmationKeys.
 * Modified the creationBehaviour in UserService to support the changes in the ConfirmationKey persistence.
 * Fixed various little things about searches for the course tests to work.
Merge with dagerenaq-DataBaseChange. All tests from Courses and Users are working. 

 * Modified the init.sql to support changes in the dabtase for ConfirmationKeys.
 * Modified the creationBehaviour in UserService to support the changes in the ConfirmationKey persistence.
 * Fixed various little things about searches for the course tests to work.