Set Fiber to the return value of require('fibers') instead of using global Fiber

See:
https://github.com/laverdet/node-fibers/issues/72

"Could you guys update your libraries to do var Fiber = require('fibers'); and replace calls to yield() with Fiber.yield(). Fiber remains unchanged otherwise."
- Updated ext and templates code to not rely on a global Fiber
- Removed 'static' reserved word (to allow latest coffeescript to build)
Merge pull request #8 from dcollien/master

updated to Fiber = require('fibers') as to work with current version of node-fibers