Purge variables in server.delFile

Closes #206
Add package dependency headers and autoload cookies for MELPA

It has been requested that we add tern.el to
MELPA (https://github.com/milkypostman/melpa/issues/925): this commit
makes some minor changes to accommodate package.el.

We plan to add two separate packages:

1. tern, containing "tern.el" and "tern-ido-complete.el"
2. tern-auto-complete, containing just "tern-auto-complete.el"

This will avoid forcing an installation of "auto-complete" upon tern
users who don't use that completion package.

So this commit adds "Package-Requires" headers as appropriate, and also
adds autoload cookies so that users will generally not need to "require"
the libraries before using them.

NOTE: the code declares "lexical-binding: t", and if this feature is
used, then the packages will not work for any of the many Emacs 23
users. As a result, I have declared dependencies on Emacs 24. If you
don't need "lexical-binding", which would be preferable, then we should
instead remove both that variable setting and the Emacs 24 dependency.
Make emacs behave correctly when completing with one option
[node plugin] Fix missing buffer builtin module

Closes #213
[node plugin] Add timers module

Issue #213
Mark version 0.4.0
Bump version number post-0.4
Prevent Package Control from zipping up the package

So Tern can install the the npm module locally.
[emacs mode] add tern-highlight-refs command
[node plugin] Add "module" module
[node plugin] Don't load binary *.node modules
[node plugin] Instantiate an AVal instead of failing for node.js stdlib modules that are not predefined
[emacs mode] rm tern-ido-complete.el
[emacs mode] Kill superfluous closing paren
Failing test case for `module.exports = require("foo")` (reassignment of module.exports to the rv of require)
[node plugin] Improve handling of module.exports

Issue #225
[node plugin] Ignore files that have a non-.js extension

Issue #219
Make sure 'prototype' appears in function object property completions

Closes #222
Log to stderr, not stdout (console.{log => error})
Remove a stray debug statement