Add go format checking on travis

[pravj]

This pull request add a source code format checking using gofmt.

It customises the build's script section and does a format check before running the test cases.

If the source code is not formatted according to the standard, it will fail the build suggesting the prospective changes.

Go code is not properly formatted. Use 'gofmt'.
diff main.go gofmt/main.go
--- /var/folders/kr/z6l_jmvs0916l5yhzzkgrysm0000gn/T/gofmt153062035	2017-04-21 12:37:03.000000000 +0530
+++ /var/folders/kr/z6l_jmvs0916l5yhzzkgrysm0000gn/T/gofmt346248406	2017-04-21 12:37:03.000000000 +0530
@@ -1,4 +1,4 @@
-package 	main
+package main
 
 import (
 	"flag"

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This change is 

[codecov]

Codecov Report

Merging #52 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #52   +/-   ##
=======================================
  Coverage   73.59%   73.59%           
=======================================
  Files          66       66           
  Lines        1530     1530           
=======================================
  Hits         1126     1126           
  Misses        378      378           
  Partials       26       26

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[pravj]

This will be a fix for #40 (Add "go fmt" to travis).

[elliotchance]

Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[elliotchance]

Awesome, thanks @pravj !

[sbinet]

apologies for coming late to the party.

instead of adding this to Travis-CI, I prefer to create a TestGofmt(t *testing.T) test (so people actually running tests will see it before bugging Travis).

see:
go-hep/hep@0b78c29

[elliotchance]

@sbinet - I like that ides.

One thing that is bugging me is we are mixing integration and unit tests with go test. I know there is a -run condition, but I can't find an easy way to exclude or run only the tests that don't match a regex?

[sbinet]

a "simple" workaround is to prefix all unit tests with Unit and all integration tests with Integ.

ie:
TestUnitFoo(t *testing.T)
TestIntegFoo(t *testing.T)

[zoeyfyi]

The standard library makes unit tests use short mode, so to run all unit tests use go test -short