supports backend storage in in-memory storage
remove Samples() Percentiles() from influxdb driver
remove Samples() Percentiles() from bigquery storage driver
panic->error
remove debug code
delete data from influxdb after unit test
glog.Infof()
remove string rep of time
parenthesis.
Merge pull request #218 from monnand/write-only-storage

Write only storage: Part 1