Update changelog for 1.0.0-beta.15 release

Update changelog for 1.0.0-beta.15 release

pin ember version in gemspec

fix blueprint for beta.14

release v1.0.0-beta.13

changelog/ember add-on update; release beta.12

add beta.11 to ember addon

package.json should reflect ember v1.0.0-beta.10

release v1.0.0-beta.9

Merge branch 'master' into beta