Unhandled exception (7373724e)

Zeus version:
`1.5.2.f6a3ad`

Firefox version:
`(57, 0)`

Geckodriver version:
`geckodriver-v0.19.0-linux64.tar.gz`

Error info:
```Traceback (most recent call last):
File "/root/zeus-scanner/var/search/selenium_search.py", line 268, in parse_search_results
tor=tor, batch=batch, xforward=forward_for
File "/root/zeus-scanner/var/search/selenium_search.py", line 82, in get_urls
browser = var.search.SetBrowser(agent=user_agent, proxy=proxy, tor=tor, xforward=xforward).set_browser()
File "/root/zeus-scanner/var/search/__init__.py", line 148, in set_browser
executable_path=whichcraft.which("geckodriver"))
File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.py", line 144, in __init__
self.service.start()
File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/common/service.py", line 93, in start
(os.path.basename(self.path), self.start_error_message, str(e)))
File "/usr/lib/python2.7/posixpath.py", line 114, in basename
i = p.rfind('/') + 1
AttributeError: 'NoneType' object has no attribute 'rfind'
```

Running details:
`Linux-4.19.0-kali4-amd64-x86_64-with-Kali-kali-rolling-kali-rolling`

Commands used:
`zeus.py -d /root/dork -D`

Log file info:
```2019-04-20 14:02:01,645;zeus-log;INFO;log file being saved to '/root/zeus-scanner/log/zeus-log-11.log'
2019-04-20 14:02:01,645;zeus-log;INFO;specified to use non-default search engine
2019-04-20 14:02:01,645;zeus-log;INFO;starting dork scan with query '/root/dork'
2019-04-20 14:02:01,645;zeus-log;WARNING;only pulling URLs with GET(query) parameters (to pull all URL's pass -E)
2019-04-20 14:02:01,645;zeus-log;INFO;attempting to gather query URL
2019-04-20 14:02:01,645;zeus-log;INFO;setting up virtual display to hide the browser
2019-04-20 14:02:01,762;zeus-log;INFO;setting the browser
2019-04-20 14:02:01,774;zeus-log;ERROR;selenium_search.pyc failed to gather the URL from search engine, caught exception ''NoneType' object has no attribute 'rfind'' exception has been logged to current log file
Traceback (most recent call last):
File "/root/zeus-scanner/var/search/selenium_search.py", line 268, in parse_search_results
tor=tor, batch=batch, xforward=forward_for
File "/root/zeus-scanner/var/search/selenium_search.py", line 82, in get_urls
browser = var.search.SetBrowser(agent=user_agent, proxy=proxy, tor=tor, xforward=xforward).set_browser()
File "/root/zeus-scanner/var/search/__init__.py", line 148, in set_browser
executable_path=whichcraft.which("geckodriver"))
File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/firefox/webdriver.py", line 144, in __init__
self.service.start()
File "/usr/local/lib/python2.7/dist-packages/selenium/webdriver/common/service.py", line 93, in start
(os.path.basename(self.path), self.start_error_message, str(e)))
File "/usr/lib/python2.7/posixpath.py", line 114, in basename
i = p.rfind('/') + 1
AttributeError: 'NoneType' object has no attribute 'rfind'

2019-04-20 14:02:09,317;zeus-log;INFO;Zeus got an unexpected error and will automatically create an issue for this error, please wait
2019-04-20 14:02:09,318;zeus-log;INFO;getting authorization
2019-04-20 14:02:09,318;zeus-log;INFO;extracting traceback from log file
2019-04-20 14:02:09,319;zeus-log;INFO;attempting to get firefox browser version
```

Start in var/search/__init__.py at SetBrowser.set_browser(), then follow the call from var/search/selenium_search.py get_urls(). Reproduce the scan with the reported Zeus command and inspect how geckodriver is located; done means the browser starts without the NoneType rfind traceback and the search proceeds.

Written by the indexing model from the issue text.