The user authentication was currently done using a cookie and following
the same style of token as the HTTP Basic authentication (i.e. a
concatenation of user and password joined with a ':' encoded with
base64).

This authentication has been replaced by a standard HTTP Basic
authentication.

This commit adds the new resource UsersResource (/users) with a simple
functionality: retrieving the data of an user. This functionality
requires knowing the login of the user that is performing the request.
In this regard, this commit is an example of how this information can be
retrieved and how to test a resource that requires knowing the login of
an user.

The tests classes have been simplified by delegating some of the
functions in the test classes to external utility classes. For example,
a PeopleDataset has been added to manage the dataset or the
IsEqualToEntity Hamcrest matcher has been added to simplify entity
comparisons.

In addition, a PersonUnitTest class has been added to test the Person
entity.

A big refactorization has been done in this commit, focused on
simplifying the testing and execution process. The Spring-DbUnit library
has been added to allow the use of DbUnit through annotations in the
test classes. This change has been complemented with two new test
listeners that allow the creation of custom initial contexts and the use
of custom SQL scripts to create and destroy the database tables before
and after the test execution, respectively. In addition, all the tests
are executed now using a HSQLDB database.

The datasource configuration has been pulled out of the project, and now
it must be provided by the container.

The sample classes have been reviewed, refactorized and documented with
JavaDoc.

The POM file has been reworked to ease test and application execution
using maven. The new execution modes are:
	- The default execution includes unit, integration and acceptance (with
Selenium) test execution.
	- No acceptance tests: mvn -P -acceptance-tests-cargo <phase>
	- Run server for manual acceptance tests: mvn
-Dcargo.tomcat.start.skip=true -Dcargo.tomcat.run.skip=false
-DskipTests=true pre-integration-test 
	- Run server with MySQL database: mvn -P
run-tomcat-mysql,-acceptance-tests-cargo -DskipTests=true package
cargo:run