[JENKINS-18643] Make tests run on Windows. Use line.separator property instead of LF.
[JENKINS-18643] Make tests run on Windows. Use local HTTP server to access update-center.json for test.
Merge pull request #854 from ikedam/feature/JENKINS-18643-1

[FIXED JENKINS-18643] Make tests run on Windows (line break character, query parameters for file schema)