Create a logic for exposing configuration structure

[MatousJobanek]

Issue Overview

In Che, we need to get information which parameters are possible to use in configuration. Based on this, we can create a window for configuring it. What we need to know:

• parameter name
• type (boolean/string/list of values to choose from)
• default value
• structure - which parameters belong to a particular config section
• description of every parameter (not essential but nice to have)

[bartoszmajsak]

ObjectMapper and ConfigurationItem can be leveraged to provide this information for Che.