update rake

it's functionally the same as 9, it just removes a bunch of
deprecated stuff we're not using

Change-Id: Iee9b6f0ae57607bbf481f6c90fd0007a3b3d9133
Reviewed-on: https://gerrit.instructure.com/18679
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Brian Palmer <brianp@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>

Gemfile

@@ -42,7 +42,7 @@ gem 'netaddr',        '1.5.0'
 gem 'nokogiri',       '1.5.5'
 gem 'oauth',          '0.4.5'
 gem 'rack',           '1.1.3'
-gem 'rake',           '< 0.10'
+gem 'rake',           '10.0.3'
 gem 'rdoc',           '3.12'
 gem 'ratom-instructure', '0.6.9', :require => "atom" # custom gem until necessary changes are merged into mainstream
 if !ONE_NINE