Add friendlier errors when no adaptor/driver found

lib/robot.js

@@ -293,7 +293,11 @@ namespace("Cylon", function() {
     // Returns the registered module name
     Robot.prototype.registerAdaptor = function(moduleName, adaptorName) {
       if (this.adaptors[adaptorName] == null) {
+        try {
           return this.adaptors[adaptorName] = require(moduleName);
+        } catch (e) {
+          this._missingModuleError(moduleName);
+        }
       }
     };
 
@@ -347,7 +351,11 @@ namespace("Cylon", function() {
     // Returns the registered module nam//
     Robot.prototype.registerDriver = function(moduleName, driverName) {
       if (this.drivers[driverName] == null) {
+        try {
           return this.drivers[driverName] = require(moduleName);
+        } catch (e) {
+          this._missingModuleError(moduleName);
+        }
       }
     };
 
@@ -358,6 +366,15 @@ namespace("Cylon", function() {
       return "[Robot name='" + this.name + "']";
     };
 
+    Robot.prototype._missingModuleError = function(module) {
+      var string = "Cannot find the '" + module + "' module. ";
+      string += "Please install it with 'npm install " + module + "' and try again.";
+
+      console.log(string);
+
+      process.emit('SIGINT');
+    };
+
     return Robot;
 
   })(EventEmitter);