Printing `calibre-parallel` output connection

### Changing `calibre-parallel` output connection

The goal is to print stdout and stderr from calibre-parallel because

* it helps locating errors (compared to not seeing stdout and stderr)

The IPC is changed from a log file to pipe because the subprocess output doesn't reach the file in these tests (in Ubuntu and Windows).

	utils/ipc/worker.py
	def main():
		print 'test_stdout'
		test_stderr

	utils/ipc/launch.py
    def close_log_file(self):
	    print 'close_log_file: ', self._file.name
        statinfo = os.stat(self._file.name)
        print 'st_size: ', statinfo.st_size
		
	close_log_file:  /tmp/calibre_0.9.17_tmp_aubqLb/MOg4Qh_worker_redirect.log
	st_size:  0

	close_log_file:  C:\Documents\Programs\cygwin\tmp\calibre_0.9.17_tmp_u3r0s4\1sdfrk_worker_redirect.log
	st_size:  0

The output from other subprocess variations is

            # args['stdout'] = subprocess.STDOUT
            args['stderr'] = self._file._fd
			
            args['stdout'] = self._file._fd
            args['stderr'] = self._file._fd
			
			OSError: [Errno 2] No such file or directory: '/tmp/calibre_0.9.17_tmp_KsLrq0/GMt72S_worker_redirect.log'
	
### Printing exception from metadata thread
	
It's beneficial to print the exception from a thread because

* it helps locating the error because the file and line is given
	
### Removing IPC file

If communication is done through a file the removal should wait for the file handle to be closed because this call

	utils/ipc/simple_worker.py
	def fork_job
		finally:
			os.remove(w.log_path)

doesn't wait for

	utils/ipc/launch.py
    def close_log_file(self):
		self._file.close()

in Windows so that the folder is not removed

	WindowsError: [Error 32] The process cannot access the file because it is being used by another process: u'C:\\Documents\\Programs\\cygwin\\tmp\\calibre_0.9.17_tmp_fi77r4\\tkzkeh_worker_redirect.log'
	
	ls /tmp|grep calibre|wc -l
	862	
	ls -t /tmp|grep calibre|tail -1
	drwxr-xr-x 1 User None        0 2012-10-27 22:42 calibre_0.9.4_tmp_0i3o3j
	ls -t /tmp|grep calibre|head -1
	drwxr-xr-x 1 User None        0 2013-02-07 01:18 calibre_0.9.17_tmp_fi77r4