Verify user provided context

[InkedCat]

We resolve user provided path without checking it, this allow anyone to create an app that have the root folder of the system context.

dockerfile.go

Push-N-Pray/cmd/server/deployment/apps/dockerfile.go

Lines 38 to 39 in f4098bd

	app.Dockerfile = utils.ResolvePath(workspace, manifest.Dockerfile)
	app.Context = utils.ResolvePath(workspace, manifest.Context)