use istanbul for code coverage

* Requires no instrumentation
* add `make test-cov` to generate coverage reports
issue 83 IE9/10: returned if this.xhr was undefined
Merge pull request #132 from asdfryan/master

Issue 83 fix: IE9/10 error
added query.eio to take protocol version from parser. Also changed Socket.protocol to take that same protocol version
capitalized eio, added a comment saying that the protocol is an int, not a string
Merge pull request #133 from asdfryan/eioversion

Issue 65 fix: Added eio query string
require 'emitter' versus 'emitter-component'

Use the github style dependency to just grab the emitter package from
github. Use the long form because short form is all sorts of broken with
npm.
Merge pull request #131 from shtylman/emitter

require 'emitter' versus 'emitter-component'
Merge pull request #130 from shtylman/coverage

use istanbul for code coverage
package: bumped `engine.io-parser`
package: bumped `engine.io-parser`
socket: implement qs support for `string`
util: implemented simple `qsParse`
Release 0.5.0
component: fix dep
*: bump emitter to 1.0.0
polling: abort payload loop if close packet is found
polling: consider the possibility of an event changing readyState
add 'drain' emit to WS
make sure to stop interval if transport closes