Ignore .babelrc through .npmignore to fix issue with react-native pac…

…kager

The react-native packager searches through all directories and parses
.babelrc config files if it finds any. This breaks the builds if these
.babelrc files are either for babel 5 or if they contain plugins unknown
to the parent project.

@see: facebook/react-native#4062

.npmignore

@@ -0,0 +1 @@
+.babelrc