Adds a series override option to hide certain series from the legend.

* public/app/components/timeSeries.js: boolean flag to decide display in
  legend and application of override option for this flag
* public/app/panels/graph/legend.js: exclude hidden series
* public/app/panels/graph/seriesOverridesCtrl.js: add legend override
  option

This fixes #2324

Fixed invalid json example, added missing comma

set mode 0640 and group grafana on /etc/grafana/grafana.ini

Minor update to documentation for MySQL sessions

fix datasource api docs

add double quotes around tags

"Not found" should only be for http path/method not found (404)
if it's about specific resources, we should be explicit for clarity

reflects change in e2f6633d

Removed some editor srv properites from data sources, they are not needed there anymore, they are in plugin.json, Closes #2283

Work arround for slower template variable dropdown when variable has many thousand values, now only top 1000 values are rendered to html, you can still search all values, Closes #2246

Fix 'paranthesis' typo to 'parenthesis'

Allow pipe ('|') in Graphite lexer

This typo is most noticable in the Graphite lexer error hint message.

Allow for Graphite lexer to understand metric names like
'net|usage_average'.

fix config flag

Support dot (.) in metric name