fix(people): correct image path, stray whitespace, and placeholder url

- barnabyjack: gallery image is Barnaby_Jack3.jpg, not .png (404 on site)
- bradsmith, bruceesquibel: strip leading spaces from contribution urls
- larrytesler: drop template placeholder url (htps://www.cyberz.tech/)

Found by the new validator in scripts/validate_people.py.

people/barnabyjack.json

@@ -49,7 +49,7 @@
       "caption": "The showman and the cash-spewing ATMs: Barnaby Jack at the 2010 Black Hat convention."
     },
     {
-      "url": "/images/Barnaby_Jack3.png",
+      "url": "/images/Barnaby_Jack3.jpg",
       "title": "Barnaby Jack shows one of his two ATM machines",
       "caption": "Barnaby Jack shows one of his two ATM machines he bought on line and has hacked into, at his San Jose home on Tuesday, Aug. 31, 2010."
     }

people/bradsmith.json

@@ -43,7 +43,7 @@
   "contributions": [
     {
       "title": "2014 - Presentation - Hacker Halted - Cracking BlueTooth for Phun and Profit",
-      "url": "  https://www.yumpu.com/en/document/view/22139939/cracking-bluetooth-for-phun-and-profit-brad-smith-hacker-halted",
+      "url": "https://www.yumpu.com/en/document/view/22139939/cracking-bluetooth-for-phun-and-profit-brad-smith-hacker-halted",
       "description": ""
     },
     {

people/bruceesquibel.json

@@ -23,17 +23,17 @@
   "contributions": [
     {
       "title": "Dr. Ripco's Last Stand",
-      "url": " https://archive.org/details/ripcoslaststand",
+      "url": "https://archive.org/details/ripcoslaststand",
       "description": "A collection of gathered media of interest to Bruce \"Dr. Ripco\" Esquibel. Archived by Jason Scott."
     },
     {
       "title": "Closing the Net",
-      "url": " http://www.costik.com/hackers.html",
+      "url": "http://www.costik.com/hackers.html",
       "description": "January 1991 issue of Reason magazine. Detailing events that took place during Operation Sun Devil."
     },
     {
       "title": "BBS Documentary Video",
-      "url": " https://archive.org/details/bbs-20040123-ripco/Doctor+Ripco+-+Tape+1.avi",
+      "url": "https://archive.org/details/bbs-20040123-ripco/Doctor+Ripco+-+Tape+1.avi",
       "description": "Full BBS Documentary Interview: Dr. Ripco"
     },
     {

people/larrytesler.json

@@ -23,7 +23,7 @@
   "contributions": [
     {
       "title": "Computer scientist",
-      "url": "htps://www.cyberz.tech/",
+      "url": "",
       "description": ""
     }
   ],