Merge pull request #70 from xephonhq/0.3.0/init-refactor

[Partial] Document refactor plan

It's been another year, but finally ...

Merge pull request #68 from xephonhq/client/grpc/copy-libtsdb-go

[client][grpc] Copy client code from libtsdb-go

[doc] Use float64 for CPU stats for easy serial

- data from `/proc/stat` should be uint64 instead of float64, but
since most tsdb supports float64, using float64 directly does not
require the explict conversion when serialize into different formats
(mostly JSON except for InfluxDB in current benchmarks)

[doc] Fix #52 revert b4f10e7

- should use IDE refactor carefully ....

[ui] Add single static graph #19

- able to graph collector's data ... in straight line, it seems the
collector is returning wrong value, even I run some CPU intensive
program, it is just a straight line
- also without aggregation, even sample at a rate of 1 second, it would
have 300 points in 5 minutes, making the graph hard to read

[collector] Add KairosDB and InfluxDB support #23

- most code are directly copy and pasted from the `bench` package
- the graph in KairosDB is pretty strange, don't know if it's the
collector's problem, or it is my system is too stable than cut the
float number into int result in a straight line