[20170427232658] Environment Variable Hotfix

[ddollar]

This update removes single quotes from an environment variable only if the value has a leading and trailing quote. For example:

$ convox env set FOO='bar'
$ echo $FOO
bar

$ convox env set FOO="bar'"
$ echo $FOO
bar'

$ convox env set FOO="'bar"
$ echo $FOO
'bar

• #2173 remove single quotes from env vars [@MiguelMoll]