openTSDB image was broken

tweaks

Conflicts:
	docs/sources/reference/templating.md

added pages, touched up some images and content  in data-sources section

Adding additional pages and updates from google doc

add basic concpets doc

adding Raj edits/additions as well as initial round of pages I created

Merge branch 'influxdb_alias_columns' of https://github.com/thuck/grafana into thuck-influxdb_alias_columns

fix(graphite): Fix for bug when using series ref (#A-Z) and referenced series is hidden in query editor. fixes #2484

With this patch it's possible to use the column name as an identifier.
This can help when we have multiple columns as it would be possible to automatic generate a legend.
Also this would help in future when grafana could support the "AS" in the query builder.

Including more special options for fill

Included "previous" and "none" as possible values for fill.
From the influxdb documentation:
 - "previous" means the values of the previous window is used.
 - "none" means that all null values are removed.

Change log file permissions from 0660 to 0644

Depending of the value a different set of operators will show up.
If regex only =~ and !~ will show up.
Any other value will show =, <>, <, >.

This should fix the case from when we migrate from a version that doesn't contain tag.operator.