updates for 0.7

[stevengj]

Among other things, this PR deprecates nbinclude(path) in favor of @nbinclude(path) in order to use the new @__MODULE__ macro in 0.7, because current_module() is disappearing in 0.7 (JuliaLang/julia#22064). Adds an nbinclude(module, path) function to evaluate in a specific module, however.

As in JuliaLang/julia#22588, we also remove the remotecall_fetch machinery (and the dependency on the Distributed module) by assuming that any node running include has access to the filesystem.