[tools] add missing dependency for 'send'
[tools] remove rewrite-sourcemaps export

avoids dependency on connect
introduce 'release' directory

the 'release' directory holds the generated
distribution files found in the 'target' directory
after running 'grunt dist'. We need them in
the git repo for scenarios where a project uses
the skylark npm module as dependency.
For now, the files in 'release' are updated manually.
remove reference to _externals.d.ts from release/skylark.d.ts
fixes for samples/scaffold