Allow users to pass in auditConfiguration objects

[jamsea]

Allow users to configure https://github.com/GoogleChrome/accessibility-developer-tools

Also fixed a typo (replace ; with ,) which was causing the plugin to fail.

[googlebot]

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[jamsea]

I signed it!

[googlebot]

CLAs look good, thanks!

[jamsea]

Hey @sjelin is this safe to merge still? We're still using a forked version of protractor-accessibility-plugin, be great to get this into master. Cheers!

[sjelin]

Sorry - I forgot about the PR! Will do a release in a few minutes