Mac: Load and run Jenkins unconditionally to prevent user confusion.

Sometimes users unload Jenkins using the launchctl -w option.
This permanently disables the Jenkins launchd job.
When the user re-installs Jenkins, he gets confused when
Jenkins doesn't load and run automatically and there is no
good error message from launchctl when it ignores the
Jenkins job because it is permanently disabled.
("nothing found to load")

Always forcing Jenkins to run after installation seems to be
the way of minimum confusion. The user is installing Jenkins
because he wants to run Jenkins, right?

- make AccountInfo a separate describable to help the UI
- added help file explaining why one might want to do this.

Add an additional option in "Let Jenkins control this Windows slave as a
Windows service" to specify a user under which the service will be run.

This allows to use a different user than "Local System" to register a
windows service.

Added as well a few fr translations for strings in this config page.

- Add min, max, step and clazz attributes if appropriate

- hudson-behavior.js checks if value of INPUT.number is an integer
- HTML5 <input type=number> checks if value of INPUT is a number (including floating point)
- It's better to change error message for INPUT.number to 'integer'

- Based on textbox.jelly
-- Attributes removed: autoCompleteField, autoCompleteDelimChar

When using HTTP full duplex connections the upstream channel can be idle for
long periods of time and the webserver will time the connection out. Jenkins
sees this and terminates the downstream channel causing the unexpected closure
of the read channel in the CLI client.

Timeout of 15 seconds is based on the 20 second default timeout as seen in
Ubuntu Oneiric Tomcat 6 installations.

property. This releases the HTTP connection in a friendly way and allows the
webserver to recycle the connection a little quicker.