Bug fix for UTF-8 check

[yoganandc]

Description

Pretty straight-forward, e was not defined causing glances to crash when encoding is not UTF-8

With this fix, a warning is appended to the log. Reproduced below:

2019-11-14 05:27:38,350 -- WARNING -- UTF-8 is mandatory for sparklines ('ascii' codec can't encode characters in position 0-39: ordinal not in range(128))

Resume

• Bug fix: yes
• New feature: no
• Fixed tickets: (none)

[coveralls]

Coverage increased (+0.009%) to 39.602% when pulling 3752f1f on yoganandc:patch-1 into 7228a91 on nicolargo:develop.

[nicolargo]

Thanks @yoganandc !