[Serusers] added sipgrep utility

[Vaclav Kubart]

There was added sipgrep utility written by Alexandr Dubovikov
<shurik at start4.info> into SER's source tree (utils/sipgrep).

It is a wrapper on ngrep which
 * filters SIP messages according number in To or From header fields
 * displays From tag, To tag, Call-ID and branch in different colours, 
   thus it is possible to trace dialogs or transactions by "one look 
   into message" ... this is really great! ;-)
 * It can store received messages into a file and show them (together)

For a bit more info see README. For other info contact author.

	Vaclav