Do not remove slashes from labels

[cmungall]

When transforming gpi to neo, we normalize the labels. This is because in the past unusual non-ascii characters have slipped in messing up everything (need to report these upstream)

This is currently too strict, e.g. we strip /, resulting in:

id: PR:000037785
name: mEPRSPhos1 Mmus

There should be a slash in the label

For now @ukemi, just type the string without the slash (sorry)

[cmungall]

Also some groups, eg FB sometimes use backslash - this is an awful choice of character...