Enable identitiy verification user hash by default

[kmiyashiro]

Context

We now are able to send pings with user_hash without breaking anything, even if Identity Verification is not enabled for an Intercom app's settings. That means there is no downside to always enabling Identity Verification on the Messenger side.

Problem

Identity verification should be enabled by everyone, we should make it as easy as possible to enable.

Approach

Enable identity verification by default in the plugin. We already have the secret, so we can just always generate the hash if we can. This removes the step to manually enable it in the plugin settings, the only step left is to enable it in the Intercom app settings.

[kmiyashiro]

@bobjflong it is always passed along via OAuth when connecting to Intercom. I think in older versions of the plugin we manually asked for the secret. In the case that the secret does not exist for any reason, we do not generate the user_hash. I don't see a way to re-enter the secret, other than the re-connect link.

[apassant]

@kmiyashiro can you please update the version number: https://github.com/intercom/intercom-wordpress/blob/master/bootstrap.php#L8

I'll merge on Monday and ship the update to https://wordpress.org/plugins/intercom/

[kmiyashiro]

@apassant done!