Reformat photolysis labels for MusicBox

[mattldawson]

From Louisa -

It would be nice when a music_box/camp_data reactions.json file is written from the cafe, if the PHOTOLYSIS reactions take out the assignments to another rate:
For example,
"MUSICA name": "jnoa->,jch2o_a",
should be written:
"MUSICA name": "jnoa",
(just remove the arrow and everything after it, if there is an arrow, or equals sign)
"MUSICA name": "jno=userdefined,",
to:
"MUSICA name": "jno",