doc: Remove mention of Travis-CI

Travis-CI is no longer user by most open-source project as they
greatly reduced their Open-Source allowance.

README.md

@@ -1,6 +1,5 @@
 # D:YAML
 
-[![travis-ci](https://travis-ci.org/dlang-community/D-YAML.svg?branch=master)](https://travis-ci.org/dlang-community/D-YAML)
 [![codecov](https://codecov.io/gh/dlang-community/D-YAML/branch/master/graph/badge.svg)](https://codecov.io/gh/dlang-community/D-YAML)
 [![code.dlang.org](https://img.shields.io/dub/v/dyaml.svg)](http://code.dlang.org/packages/dyaml)
 
@@ -68,21 +67,21 @@ Full text of the license can be found in file `LICENSE_1_0.txt` and is
 also displayed here:
 
     Boost Software License - Version 1.0 - August 17th, 2003
-    
+
     Permission is hereby granted, free of charge, to any person or organization
     obtaining a copy of the software and accompanying documentation covered by
     this license (the "Software") to use, reproduce, display, distribute,
     execute, and transmit the Software, and to prepare derivative works of the
     Software, and to permit third-parties to whom the Software is furnished to
     do so, all subject to the following:
-    
+
     The copyright notices in the Software and this entire statement, including
     the above license grant, this restriction and the following disclaimer,
     must be included in all copies of the Software, in whole or in part, and
     all derivative works of the Software, unless such copies or derivative
     works are solely in the form of machine-executable object code generated by
     a source language processor.
-    
+
     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT