get-developers: fix code style

Fix these warnings:
E202 whitespace before ']'
E203 whitespace before ':'
E302 expected 2 blank lines, found 1
E305 expected 2 blank lines after class or function definition, found 1
E711 comparison to None should be 'if cond is None:'
E741 ambiguous variable name 'l'
F401 'sys' imported but unused
W391 blank line at end of file

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>