[BUGFIX] Internal Request Engine needs to clear security context
In order to get the security tokens matching the new request created
in the internal request engine, the security context should be cleared
using the "clearContext" method. This means that the tokens will be
matched with the configuration from the routing based on the new request
and not the parent request.
This patch also contains a small enhancement which adds two additional
headers to the virtual browser's response containing the code and message
of a possible exception.
Releases: 1.1, 1.2