Fixed the correct presence for contacts with the presenceMode="msrtc".

Fixed the correct presence for contacts with the presenceMode="msrtc".
On OCS2007 the contacts works in two basic modes: msrtc and msrtc-event-categories. The problem are the contacts with msrtc mode.

I fixed using the Table 3: Conversion of legacyInterop elements and attributes to MSRTC elements and attributes.
[MS-PRES] Section 3.7.5.5

Also was fixed to use the ms-keep-alive header correctly. We are using this
header fine but only the Pidgin options "Keepalive Timeout" and "Keepalive Timeout"
were not set. This code is unecessary today. The servers LCS2005 and OCS2007
recomends to send a keep-alive message only in intervals with the value timeout="" comming in ms-keep-alive header:
ms-keep-alive: UAS; tcp=no; hop-hop=yes; end-end=no; timeout=300
[MS-CONMGMT] Section 2.2.1

If we use another value major than timeout the server disconnects us eventually.
I got this error: SSL read error
After three or four hours.
I removed that options. We don't need them anymore.