Improve ESLint ignore rules

Apparently, using unqualified `/**` patterns prevents `!` include patterns.
Using qualified glob patterns, e.g. `js/models/**/*.js`, lets us work around this.

.eslintignore

@@ -5,13 +5,15 @@ dist/**
 libtextsecure/**
 
 # these aren't ready yet, pulling files in one-by-one
-js/**
-test/**
+js/*.js
+js/models/**/*.js
+js/react/**/*.js
+js/views/**/*.js
+test/*.js
+test/models/*.js
+test/views/*.js
 /*.js
+
+# ES2015+ files
 !main.js
 !prepare_build.js
-
-# all of these files will be new
-!test/server/**/*.js
-
-# all of app/ is included