Finish up DBProfileEditor

Can now edit existing profiles as well as create new ones. Not saying it's bug free, but should be ready for testing by others.
Explicitly close output stream of external process
Add tests (currently ignored) for checking that file handles are not excessively opened

One of these tests just queries a file repeatedly, that should be platform independent. The other uses lsof and only works on unix or mac

IGV-1927
IGV-1928 #resolve