Empty values should be consistent across config methods

[pablo]

In Flash plugins, different configuration methods can result in different types of values when retrieving plugin config options, especially when dealing with null values. The player should attempt to normalize the type of returned in these scenarios.

From DaveH:

Just to clarify, the return value from get config calls (eg; player.config('tag')) on an 
empty xml flashvar tag (eg; <tag></tag>), in:
 * pre-5.4 (cannot recall which version) returns 'null'
 * 5.4 & 5.5 returns 'undefined'
 * 5.6 returns '0'
 * 5.7 returns '' (empty string)

It would be good to define the behavior all across the player so it is always handled the
same way in flashvars (for both XML and flashvar object parameters) and with playlists.

[pablo]

Let's investigate this for the next major player update; we can make sure from the start that the player's config values are consistent.