Accept users with an empty institution during OrgDB Sync

I've spotted several NullPointerExceptions in the logs for this line, probably due to users with an empty 'Institution' field. I assume that: 
```java
p.getInstitute().getOriginalName()
```
is never ```null```, but I am not sure myself. 

Indeed,
```java
p.getInstitute()
```
can be null so I added a check for that.
Could you take a look and merge the patch if it looks fine?