Update AJV to version 6

[realityking]

Fixes #107, closes #105

[realityking]

I hadn't realized that a dependency of ajv has dropped support for Node.js 4. I suspect that's not an option for har-validator, is it?

[danepowell]

I'd really love to see AJV updated, because a lot of other packages (such as Request) depend on har-validator, and this in turn creates ugly version conflicts.

For instance, the Parse library requires Request requires Har Validator requires ajv 5. Eslint requires Table requires AJV 6.

Trying to use Parse and Eslint on the same project produces warnings about peer dependency conflicts, Parse can't find ajv at runtime, and everything falls over. Blech.

Obviously it's not my decision to make, but Node.js 4 was end of life some time ago, it seems pretty reasonable to me to drop support.

[philihp]

Would love to see this merged, although it would warrant a major version bump.

Jest also requires Request which requires Har-Validator which requires Ajv 5.

[ahmadnassri]

🎉 This PR is included in version 5.1.1 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀

[epoberezkin]

@ahmadnassri it is probably worth updating schemas in har-schema to use draft-07 (as it's backwards compatible, it only requires changing $schema) - then these 2 lines can be removed:
https://github.com/ahmadnassri/node-har-validator/pull/109/files#diff-688ede0ee2da1fa3d89f2fc485f39273R11
https://github.com/ahmadnassri/node-har-validator/pull/109/files#diff-6230eb7fbf1dd2186bf1be6042c27f55R11