Adds the ability to specify an exclideFiles glob

This permits you to tell serverless to ignore files that have
similar names to the route handlers. So ignore index.test.js or
index.ts.

This fixes serverless-heaven#433 and serverless-heaven#405

It makes life better for lots of folks :-)

lib/Configuration.js

@@ -5,7 +5,7 @@
 
 const _ = require('lodash');
 
-/** 
+/**
  * Plugin defaults
  */
 const DefaultConfig = {
@@ -50,6 +50,10 @@ class Configuration {
     return this._config.includeModules;
   }
 
+  get excludeFiles() {
+    return this._config.excludeFiles;
+  }
+
   get packager() {
     return this._config.packager;
   }

lib/validate.js

@@ -33,9 +33,12 @@ module.exports = {
     const getEntryExtension = fileName => {
       const files = glob.sync(`${fileName}.*`, {
         cwd: this.serverless.config.servicePath,
-        nodir: true
+        nodir: true,
+        ignore: this.configuration.excludeFiles ? this.configuration.excludeFiles : undefined
       });
 
+      this.serverless.cli.log(files);
+
       if (_.isEmpty(files)) {
         // If we cannot find any handler we should terminate with an error
         throw new this.serverless.classes.Error(`No matching handler found for '${fileName}' in '${this.serverless.config.servicePath}'. Check your service definition.`);
@@ -117,7 +120,7 @@ module.exports = {
         return BbPromise.reject(err);
       }
     }
-    
+
     // Intermediate function to handle async webpack config
     const processConfig = _config => {
       this.webpackConfig = _config;
@@ -220,7 +223,7 @@ module.exports = {
 
       return BbPromise.resolve();
     };
-    
+
     // Webpack config can be a Promise, If it's a Promise wait for resolved config object.
     if (this.webpackConfig && _.isFunction(this.webpackConfig.then)) {
       return BbPromise.resolve(this.webpackConfig.then(config => processConfig(config)));