Converting a command to lowercase breaks a case-sensitive URL

To reproduce the bug:
1. Start the server: ./sqlmapapi.py -s
2. Start the client: ./sqlmapapi.py -c
3. Add a new task with a case-sensitive URL: new -u "http://vbox.lc/bWAPP/sqli_4.php?title=iron+man&action=search"
4. Check the log: 
...
"message": "testing connection to the target URL"
...
"message": "page not found (404)"
...
"message": "HTTP error codes detected during run:\n404 (Not Found) - 1 times"

5. Check that sqlmap.py correcty work with same parameters: ./sqlmap.py -u "http://vbox.lc/bWAPP/sqli_4.php?title=iron+man&action=search"

[INFO] testing connection to the target URL
[INFO] checking if the target is protected by some kind of WAF/IPS/IDS