fix(ota): make update scripts self-updating and add cache-busting to installers

installer_bi.lua

@@ -69,9 +69,14 @@ local function httpGet(url)
   end
 end
 
+local function getCacheBustedUrl(url)
+  local sep = url:find("?") and "&" or "?"
+  return url .. sep .. "_t=" .. tostring(os.epoch and os.epoch("utc") or math.random(1, 999999))
+end
+
 local function download(url, path, binary)
   print("Downloading: " .. path)
-  local ok, data = httpGet(url)
+  local ok, data = httpGet(getCacheBustedUrl(url))
   if not ok then
     print("Download failed: " .. tostring(data or ""))
     return false
@@ -130,7 +135,7 @@ end
 if not download(URL_PASS, "pass.dfpwm", true) then return end
 if not download(URL_ERROR, "error.dfpwm", true) then return end
 
-local okGate, gateCode = httpGet(URL_GATE)
+local okGate, gateCode = httpGet(getCacheBustedUrl(URL_GATE))
 if not okGate then
   print("Download failed: startup")
   return