New File Structure

File Structure proposal: App files centralized under 'assets'.
- Cleaner folder structure.

Simplified gruntfile.js:
- css injected as-is
- less compiled to css/less.css
- scripts injected as-is (no copy involved)
- removed unnecessary tmp and cleanup
- updated .gitignore (no longer needed to ignore gulp files)
Merge pull request #24 from ivantodorovich/refactor/fileStructure

Proposal: File Structure