Fix connection check and re-enabled i386 and armv6l support

[MichaIng]

• Re-enabled i386 and armv6l support by searching the latest major version that was compiled for those architecture: v11.x for armv6l and v9.x for i386
• Use curl "-f" option to prevent it from storing 40x error pages in variable but exiting with error code instead: https://linux.die.net/man/1/curl
• Force HTTPS connection to nodejs.org
• Coding consistency:
  • Redirect all error messages to STDERR
  • Use single quotes around arguments with no variable calls, else double quotes
  • Use double braces for all bash conditionals
  • Do not assign a variable to another via echo + command substitution overhead
  • Use consistent if-then-else format

Fixes taaem#9