[PFEM Fluid] bug when loading the Ptype

[AlejandroCornejo]

When I open the ptype (latest ptype + GiD 16.1.6d ) it returns this error message and does not allow to use it:

@AFranci @jginternational

[AlejandroCornejo]

Complete mssg:

[jginternational]

Hi @AlejandroCornejo

It is a typo in the file app.json detected in a previous issue.
#942

FIxed in a new commit in master branch