Package installer service

Ass agreed with @sitereactor i have now made this pull request where everything is made internal for now
With this pull request it is possible to import packages from core api packaging service
I had to create a variant of PackageBinarynspector.cs (variant: PackageBinaryByteInspector.cs) since the installation now works directly from package instead of having a temporary directory. 
Maybe we should consider to compile the cs / vb files located in "App_Code" and use the output for the PackageBinarynspector?
I have merged the InstallAction and UninstallAction to one class since there are exactly the same.
I have no problem with changing from using arrays to IEnumerable. Especially the InstallationSummary and the PreInstallWarnings classes needs to have this done, since i hope they will go public in some form at some point ;)