Upgrade Rails to 4.2.8

[hrishimittal]

Upgrade to latest Rails 4 version as a fix for security vulnerabilities in 4.2.5.

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This change is 

[hrishimittal]

I expect the tests to fail until #734 is merged.

[coveralls]

Coverage remained the same at 99.329% when pulling b74819b on hrishimittal:upgrade-rails into 3106b4b on shakacode:master.

[justin808]

One small comment.

Then probably OK for merge.

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Reviewed 4 of 4 files at r1.
Review status: all files reviewed at latest revision, 1 unresolved discussion, some commit checks broke.

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CHANGELOG.md, line 9 at r1 (raw file):

*Please add entries here for your pull requests.*

## [6.6.2] - 2017-02-23

you don't need to set a version and release line

I'll be doing that.

Also, this would be Fixed (maybe changed)

Added is for new functionality and requires a bump to something like 6.7.

I'm not going to do a release on bumping the version of rails used to build the gem...

the version that matters is what people use in their apps.

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Comments from Reviewable

[hrishimittal]

@justin808 Thanks for the comment. I've updated the PR. We should probably make it clear in CONTRIBUTING.md that you set the version and release.

[coveralls]

Coverage remained the same at 99.329% when pulling 14ee30e on hrishimittal:upgrade-rails into 3106b4b on shakacode:master.