update cassandra-cql gem and set encoding of cassandra.rb

The combination of these two changes fixes an issue with using extended
utf-8 chars in cql queries (including inserts)

fixes CNVS-5719

test plan: enable cassandra page views, and from a script/console run a
test query with extended utf-8 data, for instance:

PageView::EventStream.database.execute("SELECT * FROM page_views WHERE request_id = ?", "test \xEF\xBF\xBD one")

This will return no results since that request id isn't a UUID, but the
key is it shouldn't error.

Change-Id: I1dafb6165cdda65ab64267edbf9fabc4fccd783c
Reviewed-on: https://gerrit.instructure.com/20397
Reviewed-by: Brian Palmer <brianp@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Clare Strong <clare@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>

Gemfile

@@ -152,7 +152,7 @@ group :redis do
 end
 
 group :cassandra do
-  gem 'cassandra-cql', '1.1.1'
+  gem 'cassandra-cql', '1.1.5'
 end
 
 group :embedly do

lib/canvas/cassandra.rb

@@ -1,3 +1,4 @@
+# encoding: utf-8
 #
 # Copyright (C) 2012 Instructure, Inc.
 #