Cronicle does not accept arrays as envvars

[nicholasamorim]

Solves #19.

The image currently hangs on the initial screen, with a blank frame. After investigation, the removed env was causing the problem.

Cronicle docs state:

Almost every configuration property can be overridden using this environment variable syntax. The only exceptions are things like arrays, e.g. log_columns and socket_io_transports.