[TAP] Add support for user identification in the configuration file. Besides, each time a property expected as an integer is not an integer, an exception is thrown.

[TAP] Add a parameter to limit the number of running asynchronous jobs in the configuration file: max_async_jobs.

[TAP] Add metadata support in the configuration file. Two methods to get metadata: 1/ Parse an XML file implementing the schema TableSet, and then re-build TAP_SCHEMA in the database, 2/ Get metadata from the database schema TAP_SCHEMA.

[TAP] Remove the availability fields from the configuration file. The Service will always start as available ; there is indeed no reason to start and leave it as unavailable.

+ Add the management of the Output Limit in TAPConfiguration
+ All the corresponding JUnit Tests
+ Replacing .properties test files for JUnit by a construction of Properties object
+ Update of the HTML documentation page and of the Full example file

TAP: Missing NULL test (if the property JDBC URL is not provided a NullPointerException would have occurred)

TAP+TEST: First steps with the TAP configuration file management (Factory, ServiceConnection, but not yet Metadata) + their JUnit tests + documentation (the html file + configuration file examples)