Merge pull request #3 from nemomobile/staging

[os] single quoted params for commands executed in shell
[pkgconfig] backward compatibility with old qtaround

There was no qtaround namespace

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[tests] tests for tryLock

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
test each part in a separate step

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[subprocess] fixing rc, adding start() wrapper

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>
[os] df/free: do not rely on btrfs tool presence

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jolla.com>