Add option for service name

Currently enforces either "notifo" or "boxcar", but does not yet change
any behaviors in the rest of the module.  Also prevents appending or
prepending to the option value.

Issue #226

README.md

@@ -53,6 +53,7 @@ Then set your Notifo username and API secret.  The API secret is not your passwo
 can be obtained by logging into Notifo's website, clicking Settings, and then "Click to
 Show" next to the "API Secret" heading:
 
+    /msg *push set service notifo
     /msg *push set username foo
 	/msg *push set secret ...
 
@@ -70,6 +71,7 @@ to set your configuration all over again:
 
     /msg *notifo save /tmp/znc_notifo
     /msg *push load /tmp/znc_notifo
+    /msg *push set service notifo
 
 
 Commands

push.cpp

@@ -88,7 +88,8 @@ class CPushMod : public CModule
 			// Current user
 			user = GetUser();
 
-			// Notifo user account and secret
+			// Push service information
+			defaults["service"] = "";
 			defaults["username"] = "";
 			defaults["secret"] = "";
 
@@ -782,16 +783,35 @@ class CPushMod : public CModule
 				}
 				else
 				{
+					value.Trim();
+
 					if (option == "channel_conditions" || option == "query_conditions")
 					{
 						if (value != "all")
 						{
 							eval(value);
 						}
 					}
+					else if (option == "service")
+					{
+						value.MakeLower();
+
+						if (value == "notifo")
+						{
+							PutModule("Note: Notifo requires setting both 'username' and 'secret' options");
+						}
+						else if (value == "boxcar")
+						{
+							PutModule("Note: Boxcar requires setting the 'username' option");
+						}
+						else
+						{
+							PutModule("Error: unknown service name");
+							return;
+						}
+					}
 
 					options[option] = value;
-					options[option].Trim();
 					SetNV(option, options[option]);
 
 					authencode();
@@ -814,6 +834,10 @@ class CPushMod : public CModule
 				{
 					PutModule("Error: invalid option name");
 				}
+				else if (option == "service")
+				{
+					PutModule("Error: cannot append to this option");
+				}
 				else
 				{
 					options[option] += " " + value;
@@ -840,6 +864,10 @@ class CPushMod : public CModule
 				{
 					PutModule("Error: invalid option name");
 				}
+				else if (option == "service")
+				{
+					PutModule("Error: cannot prepend to this option");
+				}
 				else
 				{
 					options[option] = value + " " + options[option];