Do not shadow global XMLHttpRequest

If you use the XMLHttpRequest variable name then the if
typeof XMLHttpRequest === 'undefined' check will always
return false and the XHR polling method is never used.

This is needed because JSONP polling is buggy and doesn't emit
close when server shutsdown. JSONP should be fixed / disabled.
Merge pull request #89 from Raynos/xhr

Do not shadow global XMLHttpRequest
client now ignores unsupported upgrades
Release 0.4.1
Merge pull request #90 from ruxkor/to_learnboost_20130117

client now ignores unsupported upgrades
fix "TypeError: Object #<Object> has no method 'global'"
Merge pull request #91 from ramitos/patch-1

fix "TypeError: Object #<Object> has no method 'global'"
parser.js: removed the file
package.json: added the engine.io-parser dependency
everything else: switched to engine.io-parser
Merge pull request #93 from sweetieSong/add/engine.io-parser

Integrated the enine.io-parser
Update component.json
Update component.json
Update component.json
Merge pull request #94 from timmak/master

Updated component to 4.1
close also if socket.readyState is on "opening"
Merge pull request #95 from pokermania/to_learnboost_20130130

close also if socket.readyState is on "opening"
polling-jsonp: fix ie6 JSONP on SSL
Release 0.4.2
package: removed unusued `parser.js`
Release 0.4.3
Added missing colon in payload. Thanks @lsm