escape open square brackets

Fix teamcity warning for messages like:

    [Step 4/4] ##teamcity[message text='The [Entity|] |'this is a test|' was inserted!' status='NORMAL' timestamp='2013-02-13T21:50:04.017+0000' flowId='262144']
    [Step 4/4] Incorrect property name.
    Valid property list format is (name( )*=( )*'escaped_value'( )*)* where escape simbol is "|"