cnPilot E400 add import config via sftp, and https functionality

Current function-->

E400(config)# import config

a TFTP or FTP server path (Eg: tftp://1.2.3.4/config.txt, ftp://user:pass@1.2.3.4/config.txt)

Requested enhancement-->

E400(config)# import config

a TFTP, FTP, SFTP or HTTPS server path

(Eg: tftp://1.2.3.4/config.txt, ftp://user:pass@1.2.3.4/config.txt, sftp://user:pass@1.2.3.4/config.txt,

https://1.2.3.4/e400magic/?)

sftp and https allows for more secure transfer of config information and https allows for extensibility at the URL level for dynamic configuatations in addition to the static configs tha tcan be reached via TFTP, FTP, SFTP