Travis-ci:added support for ppc64le

[sanjaymsh]

Hi,
I have added support for ppc64le build on travis-ci in the branch on behalf of IBM. The travis-ci build log can be tracked on the link :https://travis-ci.com/github/sanjaymsh/traildb/builds/210305950 . I believe it is ready for the final review and merge.
Please have a look on it.

Thanks !!

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[coveralls]

Coverage decreased (-0.2%) to 77.8% when pulling 72ebc97 on sanjaymsh:ppc64le into 053ed8e on traildb:master.