Added timezone support for datetime fields in PSQL

This patch adds correct timezone support in PSQL plugin. Prior to this
patch, no timezone support was provided, so only the following case
worked :
 * using local time in both client application and postgresql server
 * datetime were using second precision

This patch tries to take care that postgresql has two different
datatypes for date time, respectively :
 * timestamp with time zone
 * timestamp without time zone

Both are internally stored as UTC values, but are not parsed the same.
 * timestamp with time zone assumes that there is a time zone
   information and will parse date time accordingly, and then, convert
   into UTC before storing them
 * timestamp without time zone assumes that there is no time zone
   information and will silently ignore any, unless the datetime is
   explicitly specified as having a time zone, in case it will convert
   it into UTC before storing it

Both are retrieved as local time values, with the following difference
 * timestamp with time zone includes the timezone information
   (2014-02-12 10:20:12+0100 for example)
 * timestamp without time zone does not include it

The patch does the following :
 * parse the date retrieved by postgresql server using QDateTime
   functions, which work correctly
 * always convert the date to UTC before giving it to postgresql
 * force time zone so that timezone information is taken into account
   by postgresql
 * also adds the milliseconds when storing QDateTime values

The following configurations are tested to work :
 * client and server using same timezone, timestamp with or without tz
 * client and server using different timezone, timestamp with tz

The following configuration will *not* work :
 * client and server using different timezones, timestamp without tz

Because data will be converted to local time by the postgresql server,
so when returned it will be different from what had been serialized.
Prior to this patch, it gave the illusion to work because since TZ
information was lost, time was stored as local time from postgresql.
Lots of inconsistencies occurred, though, in case client tz changes...

I don't expect this to be an issue since having different TZ in server
and client and *not* handling this is a broken setup anyway.

Almost based on changes proposed by julien.blanc@nmc-company.fr

[ChangeLog][QtSql] Added timezone support for datetime fields in PSQL

Task-number: QTBUG-36211
Change-Id: I5650a5ef60cb3f14f0ab619825612831c7e90c12
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
QODBC: fix converted string values empty SQLServer 2012

SQL Server 2012 Native Client (version 11.0.2100.60) or later introduced
a change in the behavior of the SQLGetData method when converted string values
are involved. In older version a (sometimes wrong) size was returned. Now always
SQL_NO_TOTAL is returned which signals to read as much data as available.
SQL_NO_TOTAL was handled like SQL_NULL_DATA in the code before which indicates a
NULL value so the returned string was empty.

See link for more info: http://msdn.microsoft.com/en-us/library/jj219209.aspx

Change-Id: Ia0d2296caf593890b301ee1848d1bf3eb8d7b6fe
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
[QDateTime] ISO Time zone designators can be [+-]HH

Added support on QDateTime::fromString to read correctly dates on ISO
format with Time zone designators at format [+-]HH

Change-Id: Ied5c3b7950aee3d0879af0e05398081395c18df5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Mark Brand <mabrand@mabrand.nl>
Added ROUND test for PostgreSQL

The ROUND function for PostgreSQL only accept NUMERIC field as argument

Change-Id: I0c3753bfe4167cd47158e21b407cca8771816104
Reviewed-by: Mark Brand <mabrand@mabrand.nl>