add an optional blacklist file

The contents of this file (containing a listing of additional
domains in 'hosts' file format) are appended to the unified hosts
file during the update process.

updateHostsFile.py

@@ -96,6 +96,7 @@ defaults = {
     "exclusionregexs" : [],
     "exclusions" : [],
     "commonexclusions" : ["hulu.com"],
+    "blacklistfile" : os.path.join(BASEDIR_PATH, "blacklist"),
     "whitelistfile" : os.path.join(BASEDIR_PATH, "whitelist")}
 
 def main():
@@ -300,6 +301,11 @@ def createInitialFile():
             #Done in a cross-python way
             writeData(mergeFile, curFile.read())
 
+    if os.path.isfile(settings["blacklistfile"]):
+        with open(settings["blacklistfile"], "r") as curFile:
+            #Done in a cross-python way
+            writeData(mergeFile, curFile.read())
+
     return mergeFile
 
 def removeDupsAndExcl(mergeFile):