Update README.md

Author: pgleeson

README.md

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 # exprparser 
 
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-[![Build Status](https://travis-ci.org/LEMS/expr-parser.svg?branch=master)](https://travis-ci.org/LEMS/expr-parser)
+[![Build Status](https://travis-ci.com/LEMS/expr-parser.svg?branch=master)](https://travis-ci.com/LEMS/expr-parser)
 
 
 Mathematical expression parser, based on [Antlr4](http://www.antlr.org/). Sample visitors for algebraic / boolean expression evaluation (including lists of interdependent expressions), dimensional analysis are provided.