fix(issue): IssueService.Search() with a not empty JQL triggers 400 bad request (#292)

The JQL search term is escaped twice.

closes issue #291

examples/jql/main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+
+	jira "github.com/andygrunwald/go-jira"
+)
+
+func main() {
+	jiraClient, _ := jira.NewClient(nil, "https://issues.apache.org/jira/")
+
+	// Running JQL query
+
+	jql := "project = Mesos and type = Bug and Status NOT IN (Resolved)"
+	fmt.Printf("Usecase: Running a JQL query '%s'\n", jql)
+	issues, resp, err := jiraClient.Issue.Search(jql, nil)
+	if err != nil {
+		panic(err)
+	}
+	outputResponse(issues, resp)
+
+	fmt.Println("")
+	fmt.Println("")
+
+	// Running an empty JQL query to get all tickets
+	jql = ""
+	fmt.Printf("Usecase: Running an empty JQL query to get all tickets\n")
+	issues, resp, err = jiraClient.Issue.Search(jql, nil)
+	if err != nil {
+		panic(err)
+	}
+	outputResponse(issues, resp)
+}
+
+func outputResponse(issues []jira.Issue, resp *jira.Response) {
+	fmt.Printf("Call to %s\n", resp.Request.URL)
+	fmt.Printf("Response Code: %d\n", resp.StatusCode)
+	fmt.Println("==================================")
+	for _, i := range issues {
+		fmt.Printf("%s (%s/%s): %+v\n", i.Key, i.Fields.Type.Name, i.Fields.Priority.Name, i.Fields.Summary)
+	}
+}