Create web app task for axiom-shell.
Add static http server task to run web_app.

* Due to a Chrome bug (crbug/341909), html imports don't work on page loaded from the local file system, so we have to run the axiom-shell web app form a local server for testing.
Fix polymer loading issue.
Fix typo.

Axiom-shell app is now working end-2-end.
Move polymer components to "lib/polymer"

These components are shared between the Chrome App and the Web App.
Fix issue with hterm.
Convert CRLF to LF.
Minor cleanup.
Create startup code specific to web app.
refactor export builtin

Refactor export into env-set, env-get, and env-del
fix cd command
ArgSigils for everyone.

This decorates the existing exe's and builtins for the just-added
argSigil support.  Removes boilerplate type checking, and makes the
shell a bit smarter about command line argument parsing.
Revert change to chrome app code (not needed anymore).
Merge pull request #2 from rpaquay/create-web-app

Create web app target for axiom-shell.
Add global readline kill ring.
wait for polymer to be ready.
serve the web_app on all network interfaces.
exe/echo.js: Return a promise
return existing chrome app window before creating one
rename requireModule to __axiomRequire__, expose in environment

Adds defineModule and requireModule methods to the environment,
though the former deals with axiom modules, and the latter with
es6 modules.