Time span selection and chart navigation implemented
Small fixes

- Chart navigation button changed, it was counter intuitive.
- Cache expiration raised to 48 hours.
Clear db cache feature implemented.
Form validation implemented.
Small design fixed.
Some unit tests implemented
Merge branch 'master' of github.com:rflbras/lmtt
Merge branch 'master' of github.com:rflbras/lmtt