Some minor changes have been done to update the project and adapt it
to some depencencies updates.

The default authentication plugin for MySQL has been changed from
mysql_native_password to caching_sha2_password in version 8.0.4. This
causes that an access failure for the user created in the database
scripts when trying to login from Tomcat.

This commit changes the MySQL database scripts to maintain the
compatibility between Tomcat and MySQL in versions 8.0.4+.

Minor changes have been done in the SQL scripts to make them
compatible with MySQL 8. The main change is the way that the user is
created.

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This authentication has been replaced by a standard HTTP Basic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.

Database encoding has been changed to UTF-8. This should solve character
presentation errors in Windows environments.

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.

Some columns of the MySQL database created by the scripts in the "db"
directory where incorrectly set as nullable. This commit fixes this
error and sets them as non nullable columns.

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