Show logs to the console in 'phd debug'

Summary:
Currently we send logs to the logfile in 'phd debug', but we should send them to
the console instead.

Also fixed some %C stuff which could theoretically cause problems if a user had
percentage symbols in their paths (heaven forbid).

fratrik, this or D535 might have been involved in frustrating your efforts to
debug the "sudo" stuff.

Test Plan:
Ran "phd debug irc derpderp" and "phd launch irc derpderp". In the former case,
the exception appeared in the console. In the latter, it appeared in the log.

Reviewed By: codeblock
Reviewers: codeblock, jungejason, tuomaspelkonen, aran, fratrik
CC: aran, codeblock
Differential Revision: 536