Removed an import added by PyDev

from manifest import Bundle -> nothing related to Pelix
Keep the initialized value of a service controller

If a service controller has been set to False in __init__, then it is kept to False
when instantiating the component.
Correction of read_data() in HTTPRequestHandler

Corrects a typo and adds the missing convertion from string to integer for the Content-Length header
API change for Pelix Shell: IOHandler

Commands output and input are now handled by an IOHandler,
which handles the bytes/str conversion in Python 3.
It also provides a utility method, write_line, that applies a string.format()
using the given parameters.

The core and iPOPO commands have been updated to use this new API.