Fixed URI encoding bug from java for "[]" chars in authority

See discussion at cwi-swat/rascal#498

It's a sad workaround :-1: 

1. Replace the `[` with `\0\0\uFFF0\0\0` which are quite invalid chars to occur. (and `]` as `..\uFFF1..`)
2. Create URI
3. Replace quoted placeholders with the correct placeholders (`%5B` and `%5D`)
4. Recreate the correct URI.