TACHYON-182 Add checkstyle to the maven build system so we could reduce time to do style check for contributions

TACHYON-182 Add checkstyle to the maven build system so we could reduce time to do style check for contributions following Google style.
Fixed violations reported in the current master branch.

Note that currently you need to run
  mvn checkstyle:check or mvn checkstyle:checkstyle
to run the check.

You will see some warnings on public member for Tachyon configuration classes:
  CommonConf
  MasterConf
  WorkerConf
  UserConf
due to naming of their public member as all caps.

Once we stabilize the code we could hook it to build system to fail when checkstyle fail.
Hi Haoyuan,

Ah good catch. I have tried very carefully check the toString when
refactor change
the member variables name, sorry about the miss.

Did you make the change before merging?

Thanks!

On Sunday, October 19, 2014, Haoyuan Li <notifications@github.com> wrote:

> In core/src/main/java/tachyon/master/EditLogOperation.java:
>
> >    }
> >
> >    @Override
> >    public String toString() {
> > -    return Objects.toStringHelper(this).add("type", type).add("transId", transId)
> > -        .add("parameters", parameters).toString();
> > +    return Objects.toStringHelper(this).add("type", mType).add("mTransId", mTransId)
>
> mTransId -> transId
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/amplab/tachyon/pull/473/files#r19064962>.
>