Replace curl with wp_remote methods

[jonathanstegall]

I started a branch for this, but currently it still has errors.

https://github.com/MinnPost/object-sync-for-salesforce/tree/94-wp-http-methods

In previous attempts:

• timeout errors. One possible solution to that is to make the ini value the timeout.
• SSL errors (unclear why that was happening)
• http_build_query() errors (unclear why)

In current attempt:

• when the Salesforce authorization expires, it has a PHP error instead of being caught by the log. Not clear why

[jonathanstegall]

The thing to note is that it should be possible if we can get the parameters right, because usually the wp_remote methods end up using curl anyway.

The possible deal breaker is that WordPress does a lot of stuff with the parameters. It's possible we can't get around that stuff and that is why it breaks in the plugin, but I think we don't know enough yet to establish that.