Add travis ci link to README.md
Karma: A Data Integration Tool
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+![travis ci](https://travis-ci.org/usc-isi-i2/Web-Karma.svg?branch=master)
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The Karma tutorial at https://github.com/szeke/karma-tcdl-tutorial, also check out our [DIG web site](http://usc-isi-i2.github.io/dig/), where we use Karma extensively to process > 90M web pages.
See our [release stats](http://www.somsubhra.com/github-release-stats/?username=usc-isi-i2&repository=Web-Karma)
