Bug fixes in v3

• Add check for use of HTTP protocol for HTTPS proxy (#69)
• Add no_proxy saving and loading (#70)
• Syntax fix for /apt/apt.conf (#68)
• Fix incorrect binary naming in dnf (#65)
• gsettings no_proxy save and load functionality (#66)
• Fix blank strings for HTTP/FTP/HTTPS proxy in bash/zsh (d2e34c1) and (2458738)