Add byte array comparison function

[matthme]

Comparing two Uint8Array compares the full js object and not just the bytes which means that even if two action hashe Uint8Array are the same hash, they may not be considered equal. It would be nice to have a function in the js-client allowing to compare byte arrays without having to base64 encode them first.

[mattyg]

One option would be to reexport isEqual from lodash: https://lodash.com/docs/4.17.15#isEqual