Refactor ceilomete panel code.

Move js and css code from stats.html template to horizon.ceilometer.js.

Deleted d3.v3.min.js introduced by ceilometer since horizon already
contains it.

Move bootstrap-datepicker lib to bootstrap directory.
Update chart when the to date form is changed.

Change-Id: Ifbd7b122c7b57cde33cb0bd597bf10df9fe9d95c
Remove export to pdf feature.

Change-Id: Icfae6455009eb06b15d3391abc9e03c6d96f47a2