Previously, an attribute disjunction erroneously either had no values for any of the
attributes, or it required a value for all attributes. A required value of null in an
attribute disjunction now specifies that the disjunction imposes no value on the attribute.

This also required adding support for calculating the metadata version
based on the protocol version, and sending the current protocol version
to the server as a hint.

* Add config -> preferences update function. Strip sentryDSN out of preferences and into a package variable.

* Typo

This prevents the 'use of internal package not allowed' go compile error

The struct name now matches exactly (up to idiomatic spelling differences)
with the name of the folder that it parses and updates.