ci.jpl: Quote boot/test output in a failure message

Such output may itself contain colon, as the failure message itself, which
makes hard to parse it and figure out which is which.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I419544155ee4142ea5e9722889c25e2b4c5efce8
diff --git a/jenkins/ci.jpl b/jenkins/ci.jpl
index 20774ab..0204939 100644
--- a/jenkins/ci.jpl
+++ b/jenkins/ci.jpl
@@ -571,7 +571,7 @@
                 g.verifyStatus(test_result, "lava_test", "test")
               }
               if (boot_result.toInteger() < 1 || test_result.toInteger() < 1) {
-                error("Marking job as failed due to failed boots: ${boot_output} or tests: ${test_output}")
+                error("Marking job as failed due to failed boots: \"${boot_output}\" or tests: \"${test_output}\"")
               }
             }
           }