Changed gitter to slack integration

.travis.yml

@@ -7,12 +7,7 @@ after_success:
 - ./gradlew jacocoTestReport coveralls
 - ./gradlew artifactoryPublish -PbintrayUsername="${BINTRAY_USER}" -PbintrayApiKey="${BINTRAY_KEY}"
 notifications:
-  webhooks:
-    urls:
-    - https://webhooks.gitter.im/e/9c620e84679284b7d621
-    on_success: change
-    on_failure: always
-    on_start: false
+  slack: swagger2markup:Zz5kz0SnvtG6aVvZUM8yMkER
 env:
   global:
   - secure: "SPKolgUdjIa/uJ+7/B/GPFlsa8IZg7NuZdFA8zROTaqew/xu+oX7qVGImseeBpPIEPJb02ac6hr7Y3/zvv0GJxIPtIbyDzVh73ImQUhT1ttLYGJfITAWqAPFF7RNNMtuOl3S2DLZ5OMJddkcFp00pa9nyI82Gk47B8GsaGIntAI="

src/docs/asciidoc/gradle_plugin.adoc

@@ -36,7 +36,7 @@ You can customize the task by configuring a Map of <<Swagger2Markup properties>>
 [source,groovy]
 ----
 convertSwagger2markup {
-    swaggerInput file("src/docs/swagger/swagger_petstore.yaml")
+    swaggerInput file("src/docs/swagger/swagger_petstore.yaml").getAbsolutePath()
     outputDir file("${buildDir}/asciidoc")
     config = ['swagger2markup.markupLanguage' : 'ASCIIDOC',
               'swagger2markup.pathsGroupedBy' : 'TAGS']
@@ -48,7 +48,7 @@ convertSwagger2markup {
 .Gradle Plugin properties
 |====
 | Name | Description | Type |  Example
-| swaggerInput | The URL or file path to the Swagger specification | String | `file("src/docs/swagger/swagger_petstore.yaml")` or `http://petstore.swagger.io/v2/swagger.json` 
+| swaggerInput | The URL or file path to the Swagger specification | String | `file("src/docs/swagger/swagger_petstore.yaml").getAbsolutePath()` or `http://petstore.swagger.io/v2/swagger.json` 
 | outputDir | The directory where the output should be stored. | File | `file("${buildDir}/asciidoc")` 
 | outputFile | The file path (without extension) where the output should be stored. | File | `file("${buildDir}/asciidoc/swagger")` 
 | config | The Swagger2Markup properties to configure the converter | Map |  |