Fix issues with scripts and persistent data

[FeeeeK]

Fix errors in scripts:

• ./functions.sh: line 14: [: : integer expression expected
• cp: can't stat ... (easyrsa build-client-full requires yes input)
• can't stat 'pki/ca.crt': No such file or directory #174 Can't start with volume #184

[FeeeeK]

About persistent data, I think it is worth adding an argument to the dockerfile to disable ca initialization, because the data will be replaced by volume anyway and the initialization will be done twice (which takes a very long time).

[alekslitvinenk]

Thanks a lot for your code contribution! Our team will review proposed code changes