Add time_to_live parameter into the barclamp

Add the parameter time_to_live (ceilometer.conf) into the barclamp,
so the user can decide when the meter lines are removed from the
database.

This patch was tested with a mongodb configuration.

This patch was made by Jiri (jsuchome). I only tested it and added
the parameter in the ceilometer.conf.erb template.

(cherry picked from commit d5e9682133aca62b0f266759b0f062b2f749d356)
Repair database cronjob

The server recipe create and deploy a daily cronjob that removes
related elements in the database (according to time_to_live
parameter) and a weekly job that recreate the database in case
of a mongodb database.

(cherry picked from commit 7026fe46e8a87cc963dd8737aec7d709b75acbd7)
Store the value of time to live in days, instead of seconds
to make it more user friendly.
Put TTL settings before verbose setting in webui

(cherry picked from commit 1308d4dd923ac4c9f3f8d76a015fb58956f37e0f)
Merge pull request #164 from jsuchome/time_to_live_stoney

Add time_to_live parameter into the barclamp