chore(.gitignore): fix patterns

make patterns more strict so we don't accidentaly match stuff deeply
nested in the codebase.

.gitignore

@@ -1,6 +1,4 @@
-build/
-angularjs.netrc
-jstd.log
+/build/
 .DS_Store
 gen_docs.disable
 test.disable
@@ -9,7 +7,7 @@ performance/temp*.html
 .idea/workspace.xml
 *~
 angular.js.tmproj
-node_modules
-components
+/node_modules/
+/components/
 angular.xcodeproj
 .idea