Bug 20700: MARC21 add/update leader/007/008 codes

Bug 20700: MARC21 add/update leader/007/008 codes

This add/updates some codes from updates 22 (Apr/16)
and 23 (Nov/16)

Update 22 https://www.loc.gov/marc/up22bibliographic/bdapndxg.html

Sound Recording 007/03 n (new)
Sound Recording 007/10 n (new)
Sound Recording 007/01 r (new)
Sound Recording 007/01 s (new)

Update 23 https://www.loc.gov/marc/up23bibliographic/bdapndxg.html

Leader/18 n (new)
Music 008/20 p (new), b (renamed)

To test:
1) Apply the patch
2) Clean your browser cache
3) Go to cataloguing -> new record
4) Leader plugin: check leader/18, new option 'n'
5) 007 Plugin:
a) Sound recording
	check 007/01 new 'r'
	check 007/03 new 'n'
	check 007/10 new 'n'
b) Electronic resource
	check 007/01 new 's'
6) 008 Plugin: Music, check 008/20 renamed 'b', new 'p'

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>