Remove SonarQube configuration file

Closes gh-383

sonar-project.properties

-# Required metadata
-sonar.projectKey=java-sonar-runner-simple
-sonar.projectName=Simple Java project analyzed with the SonarQube Runner
-sonar.projectVersion=1.0
-
-# Comma-separated paths to directories with sources (required)
-sonar.sources=src
-
-# Language
-sonar.language=java
-
-# Encoding of the source files
-sonar.sourceEncoding=UTF-8
\ No newline at end of file