Singlestat: Support string values

[xkrt]

Hi,

I have some string metric (which is actually string representation of date) and want just show last value of it on dashboard. So I use 'Single stat' graph with query:

SELECT last(value) FROM "my_serie"

Grafana always shows just "0", but if I run these query in InfluxDB web interface I got my result:

time                    last
1970-01-01T00:00:00Z    2015-06-20

InfluxDB ver 0.9
Grafana latest ~11 June

[torkelo]

Singlestat does not support string values yet. Wil try to fix before 2.1 release