devserver-global Makefile target is missing necessary quoting

[mpounsett]

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Issue

The devserver-global Makefile target is missing quoting around variables that is present in other targets. The missing quotes can result in errors calling pelican if any of the paths have spaces or special characters in them.

pelican -lr /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/content -o /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/output -s /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/pelicanconf.py  -b 0.0.0.0
/bin/sh: -c: line 0: syntax error near unexpected token `('
/bin/sh: -c: line 0: `pelican -lr /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/content -o /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/output -s /Users/matt/Dropbox (Personal)/Development/conundrum/personal-site/pelicanconf.py  -b 0.0.0.0'
make: *** [devserver-global] Error 2

PR incoming to address this and #3065, since it'll be easy to address that at the same time.