Update BlackberryNotification.cs
Update BlackberryNotification.cs

* Add documentation
* Change default value of DeliverBeforeTimestamp
volkd/PushSharp,volkd/PushSharp,tianhang/PushSharp,codesharpdev/PushSharp,bobqian1130/PushSharp,mao1350848579/PushSharp,tianhang/PushSharp,has-taiar/PushSharp.Web,chaoscope/PushSharp,SuPair/PushSharp,wanglj7525/PushSharp,zoser0506/PushSharp,JeffCertain/PushSharp,agran/PushSharp,JeffCertain/PushSharp,yuejunwu/PushSharp,richardvaldivieso/PushSharp,fanpan26/PushSharp,SuPair/PushSharp,profporridge/PushSharp,rolltechrick/PushSharp,cnbin/PushSharp,codesharpdev/PushSharp,ZanoMano/PushSharp,sskodje/PushSharp,kouweizhong/PushSharp,bobqian1130/PushSharp,arleyandrada/PushSharp,sumalla/PushSharp,mao1350848579/PushSharp,profporridge/PushSharp,rucila/PushSharp,18098924759/PushSharp,bobqian1130/PushSharp,cnbin/PushSharp,fhchina/PushSharp,cafeburger/PushSharp,arleyandrada/PushSharp,sumalla/PushSharp,rucila/PushSharp,agran/PushSharp,ingljo/PushSharp,mao1350848579/PushSharp,FragCoder/PushSharp,fhchina/PushSharp,sskodje/PushSharp,tianhang/PushSharp,fhchina/PushSharp,kouweizhong/PushSharp,wanglj7525/PushSharp,SuPair/PushSharp,yuejunwu/PushSharp,agran/PushSharp,zoser0506/PushSharp,wanglj7525/PushSharp,sumalla/PushSharp,volkd/PushSharp,zoser0506/PushSharp,FragCoder/PushSharp,chaoscope/PushSharp,JeffCertain/PushSharp,rolltechrick/PushSharp,chaoscope/PushSharp,cafeburger/PushSharp,has-taiar/PushSharp.Web,yuejunwu/PushSharp,rolltechrick/PushSharp,richardvaldivieso/PushSharp,FragCoder/PushSharp,sskodje/PushSharp,18098924759/PushSharp,ZanoMano/PushSharp,bberak/PushSharp,bberak/PushSharp,fanpan26/PushSharp,ingljo/PushSharp,fanpan26/PushSharp,18098924759/PushSharp,cafeburger/PushSharp,kouweizhong/PushSharp,rucila/PushSharp,richardvaldivieso/PushSharp,profporridge/PushSharp,ZanoMano/PushSharp,codesharpdev/PushSharp,ingljo/PushSharp,cnbin/PushSharp