refactor sql backend to improve write speed

- drop sourceassoc table as its data is not accessible via api
- drop resource table since data can be retreive from sample table

Change-Id: I2d4a5175734cafce6a439ad736c47691e6e7e847
Implements: blueprint big-data-sql
Closes-Bug: #1305332
Closes-Bug: #1257908
Updated from global requirements

Change-Id: If6dbe9c45926d0ecc62f858f7d466896ac1872a4
Update the copyright date in doc

This patch modifies the doc/conf.py file to contain the proper date
for the copyright text.

Change-Id: I18071dac9b3fd8bb2a49f31b97330ddc4ae614c8
Ignore the generated file ceilometer.conf.sample

Since we have removed the ceilometer.conf.sample file and added
tox -e genconfig to generate it, we should no longer track it.

Change-Id: I66a03eb2672941ba5115bf0adb9fb0c944f68e4d
Closes-Bug: #1320150
Merge "Ignore the generated file ceilometer.conf.sample"