[UWS] End of 'Fix synchronization bug while generating the default Job ID' (commit e6a9d52f)

[UWS] Make XML representation of jobs and joblists valid (with their XML schema), and particularly the nodes jobs, job and the error type (which should be written in lower-case).

[UWS,TAP] Fix timestamp format. Now, each returned date will expressed in UTC and using the ISO8601 format. Any given date is also expected in UTC (or with a time zone offset) and in ISO8601Format. These rules apply also for uploaded tables and for timestamp columns in a query result.

[TAP,UWS] Make valid VOTable results and errors. Some error messages about expected TAP request parameters have been changed.

[TAP,UWS] Fix a problem with the format of the error details returned by the parameter .../error/details. In TAP a VOTable document is expected, but a text/plain description was returned (default behavior in the UWS lib.). Now, a ServiceErrorWriter is used to format the error details correctly.

[TAP,UWS] Small log corrections (for Thread logs, display the thread name rather than the ID ; the job id was forgotten in the log of CHANGE_PHASE ; build a UWSException with the given throwable message as message ; in log TAP for the event EXECUTING, the memory address of the ADQLQuery object was displayed rather than of the ADQL query expression ; display the stack trace of the SQLException.getNextException() when calling logDB)

[TAP,UWS] Manage thrown Error properly in synchronous and asynchronous jobs execution + Modify some log messages + Add log messages in JDBCConnection (for add and drop uploaded tables).

[UWS,TAP] Review the exceptions and logs management + Add log file rotation (with a configurable rotation frequency)

[UWS] Improve the test of an URL: it may be null or the interesting part of it can be ; the two cases must be tested.