Linked up tags to headings and added issue numbers

Each version now has a link to its release information. Each item that has a issue associated with it now has a link to that issue.

before:
## 1.1.0 (21 September, 2013)

* Add Roadmap and Contributors to `README.md`
* Move `img`, `css`, `js`, `fonts` folders into new `assets` for tidier scaffolding
* Add `grunt-dev.bat` and `grunt-build.bat` for Windows support double-click commands
* Small `Gruntfile.js` tweaks for `assets` object



after:
## [1.1.0](https://github.com/toddmotto/fireshell/releases/tag/v1.1.0) (21 September, 2013)

* Add Roadmap and Contributors to `README.md`
* Move `img`, `css`, `js`, `fonts` folders into new `assets` for tidier scaffolding ([#8](https://github.com/toddmotto/fireshell/pull/8))
* Add `grunt-dev.bat` and `grunt-build.bat` for Windows support double-click commands ([#7](https://github.com/toddmotto/fireshell/pull/7))
* Small `Gruntfile.js` tweaks for `assets` object