Packages.csv: Add Pharmacy Enterprise Customization System (PECS)

Add this application package with VistA namespace PREC.  See VDL entry:

 http://www.va.gov/vdl/application.asp?appid=204

and v2.2 release announcement patch 'PREC*2.2*1'.

Change-Id: I93f2ec80020824e86fbd093340c5f97ac56d9756