Moved install.inf related code from save_network to new client.

save_network client used to be run in the end of first stage. However,
installer needs configured network at the beginning of first stage since
first and second stages were merged. Install.inf is one of resources
usable for "automatic" network configuration.
Refactoring: "new" InstInstallInfClient
Refactoring: InstInstallInfClient - splitting methods
Dropped dead code
Refactoring: removed globals from InstInstallInfClient
Turned InstInstallInfClient into singleton using ruby way.
Cleaning the code in InstInstallInfClient.
InstInstallInfClient: made "helpers" private
Refactoring: InstInstallInfClient - splitted CreateOtherNetworkFiles
Use new logger in InstInstallInfClient
Refactoring: Made InstallInf class inner class of InstInstallInfClient
Moved install.inf handling code from client class into a lib class

Whole code was located in InstInstallInfClient class. For better
testability and cleaner design it was moved into new dedicated class
under lib.
Created testsuite for InstallInfConvertor
Renamed CamelCase methods
Moved code configuring network storage accessed via iBFT capable device

back to save_network. It cannot be done earlier - depends on Storage.
Extended testsuite for InstallInfConvertor
Updated changelog
Merge pull request #158 from mchf/bnc859213-install-inf

Client for configuring network according install.inf