run coveralls when running build with code coverage

.travis.yml

@@ -56,4 +56,4 @@ script:
 
 after_success:
     ## Coveralls
-    - if [ -z "$COVERAGE" ]; then travis_retry php vendor/bin/php-coveralls -v ; fi
+    - if [ -n "$COVERAGE" ]; then travis_retry php vendor/bin/php-coveralls -v ; fi

composer.json

@@ -61,8 +61,7 @@
         "php": "^5.3.3 || ^7.0",
         "ext-xml": "*",
         "zendframework/zend-escaper": "^2.2",
-        "phpoffice/common": "^0.2",
-        "php-coveralls/php-coveralls": "1.1.0"
+        "phpoffice/common": "^0.2"
     },
     "require-dev": {
         "phpunit/phpunit": "^4.8.36 || ^5.0",
@@ -73,7 +72,8 @@
         "phploc/phploc": "2.* || 3.* || 4.*",
         "dompdf/dompdf":"0.8.*",
         "tecnickcom/tcpdf": "6.*",
-        "mpdf/mpdf": "5.* || 6.* || 7.*"
+        "mpdf/mpdf": "5.* || 6.* || 7.*",
+        "php-coveralls/php-coveralls": "1.1.0 || ^2.0"
     },
     "suggest": {
         "ext-zip": "Allows writing OOXML and ODF",