Properly encode our test file URLs

Discovered this when running tests in a directory which has a space in the path.
File.toURL() is deprecated in the JDK anyways:

    This method does not automatically escape characters that are illegal in
    URLs. It is recommended that new code convert an abstract pathname into a URL
    by first converting it into a URI, via the toURI method, and then converting
    the URI into a URL via the URI.toURL method.

Fixes #280

Author: R. Tyler Croy

jruby-gradle-base-plugin/src/integTest/groovy/com/github/jrubygradle/JRubyExecExtensionIntegrationSpec.groovy

@@ -93,7 +93,8 @@ class JRubyExecExtensionIntegrationSpec extends Specification {
         }
 
         then:
-        outputBuffer == "[\"${new File(TEST_JARS_DIR, 'org/bouncycastle/bcprov-jdk15on/1.46/bcprov-jdk15on-1.46.jar').toURL()}\"]"
+        def outputFile = new File(TEST_JARS_DIR, 'org/bouncycastle/bcprov-jdk15on/1.46/bcprov-jdk15on-1.46.jar')
+        outputBuffer == "[\"${outputFile.toURI().toURL()}\"]"
     }
 
     def "Running a script that requires a gem, a separate jRuby and a separate configuration"() {