newaccountmodel: adds save and load for complete account config

- adds ConfProperties structure in account::Info
- binds accountDetailsChanged signal in ConfigurationManagaer
- call NewAccountModel::getAccountConfig to get a copy
  of the current account details
- call NewAccountModel::setAccountConfig with a ConfProperties
  struct as a parameter to save any configuration changes
- enabled, alias, and username (in the case of SIP) will have
  seperate setters for now
- device name setting can be changed using the NewDeviceModel API
- WARNING: if the account details map won't be directly used
  to manage an account configuration detail, then the details
  should be removed from the ConfProperties_t struct and
  ConfProperties_t::toDetails and Info::fromDetails

Change-Id: I666da2ce9750befaa358ba5319e14ecbaf2cec0d
Reviewed-by: Sebastien Blin <sebastien.blin@savoirfairelinux.com>