Upgrade to emissary 0.31.0 for implicit 'value' subscriptions on signals

Previously, when you always had to specify the event name of 'value'
when calling `::subscribe` with a signal. Now, if you don't specify an
event name, 'value' is assumed.

src/tokenized-buffer.coffee

@@ -35,7 +35,7 @@ class TokenizedBuffer extends Model
     @subscribe @buffer, "changed", (e) => @handleBufferChange(e)
     @subscribe @buffer, "path-changed", => @bufferPath = @buffer.getPath()
 
-    @subscribe @$tabLength.changes.onValue (tabLength) =>
+    @subscribe @$tabLength.changes, (tabLength) =>
       lastRow = @buffer.getLastRow()
       @tokenizedLines = @buildPlaceholderTokenizedLinesForRows(0, lastRow)
       @invalidateRow(0)