added badges [skip cli]

Author: MarioRuiz

README.md

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 [![Gem Version](https://badge.fury.io/rb/string_pattern.svg)](https://rubygems.org/gems/string_pattern)
 [![Build Status](https://travis-ci.com/MarioRuiz/string_pattern.svg?branch=master)](https://github.com/MarioRuiz/string_pattern)
 [![Coverage Status](https://coveralls.io/repos/github/MarioRuiz/string_pattern/badge.svg?branch=master)](https://coveralls.io/github/MarioRuiz/string_pattern?branch=master)
+![Gem](https://img.shields.io/gem/dt/string_pattern)
+![GitHub commit activity](https://img.shields.io/github/commit-activity/y/MarioRuiz/string_pattern)
+![GitHub last commit](https://img.shields.io/github/last-commit/MarioRuiz/string_pattern)
+![GitHub code size in bytes](https://img.shields.io/github/languages/code-size/MarioRuiz/string_pattern)
+
 
 With this gem, you can easily generate strings supplying a very simple pattern. Even generate random words in English or Spanish.
 Also, you can validate if a text fulfills a specific pattern or even generate a string following a pattern and returning the wrong length, value... for testing your applications. Perfect to be used in test data factories.