namespaces reorganization

namespaces reorganization

* common_installer {} - this namespace includes all app-installers definitions
  (Step,  ContextInstaller, utils, AppInstaller)

* utils {} - this namespace includes all extra definitions that are
  not directly related to app-installer framework and are used within
  the project (eg. logging, "dirs" handling, design patterns primitives
  (eg. singleton) etc)

* common/unzip {} - this is a namespace that includes unzipping step
  and its additional definitions

* common/signature {} - this is a namespace that includes signature step
  and its additional definitions

* common/copy {}, common/register {}, etc - these namespaces are
  analogic to unzip or signature

* wgt {} - this is a namespace that includes definitions specified for
  wgt type installation

* wgt/parse {} - this is a namespace that includes parsing step
  specified for wgt type installation

Change-Id: I9fbc542e9184def7bbd6955837c506ccf32825e3
Signed-off-by: Pawel Sikorski <p.sikorski@samsung.com>
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>