Remove a stray word from the inline docs on the logs screen
Unslash the points change reason from the profile page before saving it

Otherwise we’ll be double-shashing data.
Explicitly mark WordPoints_Registration_Points_Hook::logs() as public
Let the drop down builder accept options as arrays/objects

The key to use for the option values is specified by the `’values_key’`
argument. The `’options_key’` argument specifies the key for the
options’ text.

Includes a small tweak so that the `selected=“selected”` won’t get
echoed twice.

Also adds unit tests for the dropdown builder.

Fixes #49
Make the (get|the)_field_(name|id) functions of the points hook class public

Also move the `init()` function down with the other protected methods.

Spurred by work on #4
Add a description field to all points hooks forms

This lets the user give each hook instance a custom description, which
defaults to the hook’s general description.

See #4