android/IOIOHelper: catch ContextWrapperDependent.open() exceptions

Some failure inside AccessoryConnectionBootstrap.open() is probably
the cause of the crash described in TRAC #3309.
android/IOIOHelper: catch exceptions in openUart()

If all else fails, catch the exception in this method called by native
code.  The C++ method IOIOHelper::openUart() does not check for
exceptions, thus we need to do it in Java code.