use updated watson commit (#9)

This includes the fix for stdout output

Author: wfleming

Dockerfile

@@ -2,10 +2,10 @@ FROM alpine:edge
 
 WORKDIR /usr/src/app
 
-RUN apk --update add nodejs git ruby ruby-dev build-base && \
+RUN apk --update add nodejs git ruby ruby-dev ruby-json build-base && \
   apk del build-base && rm -fr /usr/share/ri
 
-RUN npm install -g mrb/ember-watson.git#95387b7
+RUN npm install -g mrb/ember-watson.git#7dacf719
 
 COPY . /usr/src/app