Move static footer out of wrap to the help tab
Set up mail-content iframe style in the css
Reorganize page layout

- Use fixed NavBar instead of static one
- Use fixed position for #mail-content iframe
- Remove manual height adjustment after loading
- Remove Bootstrap responsive CSS
Adjust NavBar formatting (#40)
Clean up indent
Merge pull request #41 from tomyun/layout

기본 페이지 레이아웃 변경