Improvements - Was "Communication with CentralReport Online"

## Update 03/03/2014

CentralReport Online is not planned anymore. Another project will be born in few days and will be announced on the [CR blog](http://blog.centralreport.net).
As this pull request adds useful features and many improvements in the core of this project, this branch has been merged into develop.

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### Original pull request:
This pull request adds the communication with CentralReport Online (centralreport.net).
CentralReport Online is an online tool to follow all your hosts, in a single place. This part is currently in development and will be enhanced in the next weeks.

 - [x] Add "requests" library
 - [x] Create the "webservice" module
 - [x] Create webservices entities
 - [x] Clean and code optimization 

Remains to be done:
 - [x] Clean values from the collector ('\n' in some variables, or too many spaces in others)
 - [x] Clean useless entities ("Full", "Registration")
 - [x] Compact the JSON output (on a single line, without useless spaces)
 - [x] Cast dates and float to long (like disk spaces or memory data)
 - [x] Update the thread "Checks" to send data to the Online part
 - [x] Do more tests with the JSON generation
 - [x] Add the "Agent name" and "Agent version" in the host json.

_Updated tasks (miniche, 02/04/2013)_
_Updated tasks (miniche, 29/05/2013)_
_Updated title and description (miniche, 30/07/2013)_