Clean-up and making ENTRYPOINT preferred form...

Adding clean-up RUN, and making ENTRYPOINT the preferred form.
Merge pull request #5 from JasonSwindle/patch-3

Clean-up and making ENTRYPOINT preferred form...
Use ContainerStatsSample to store samples because CPU usages are
cumilative
unit tests for stats sample
create sample from a constructor
usge container stats sample
unit test for sampling
quickstart/Dockerfile: cleanup

switch to google/debian:wheezy / libprotobuf7
remove apt-get upgrade (you should rely on the base image being updated)
add --no-install-recommends
remove cleanup at the end (it doesn't save space, as the file already are in previous layers)
Merge pull request #10 from proppy/master

quickstart/Dockerfile: cleanup
ignore sample if it leads cpu utilization < 0
unit test for NewSample()
change comments
remove avg memory usage
gofmt -r "ContainerStatsSummary->ContainerStatsPercentiles"
remove float opts.
Ignore the error because its' same as nil sample
correct a unit test
comment for intZipuint64
change var names
set timestamp by default. This behavior cannot be changed by users