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.

This patch includes some missing comparators/operators for influxdb:
>  - greater than
<  - less than
<> - not equal
!~ - doesn't match against

It includes the tag.operator fields to facilitate identification of the operators on the segments.
It keeps the logic for the regex syntax; although it changes the way to validate it, to handle the new operators use case.

Including non_negative_derivative function on influxdb

Since version 0.9.0 of influxdb the non_negative_derivative function
is merged, this small patch includes it as an option on grafana.

Allow default org role to be Read Only Editor

fix(influxdb): fix for using template variables in side alias field in influxdb 0.9 editor, fixes #2446

fix(templating): fix for text panel when using template variables in text and repeating panel, fixes #2442