Performance improvement when providing bundle id

[vdesabou]

This pull request is done to avoid as much as possible the use of exec() in Workflows constructor. When providing bundled when creating Workflows, I get good improvements.

I've created a workflow to show the improvements, get it here https://cloudup.com/cBiUwDy104X

See:

[vdesabou]

Hi David,

I've added some details here as well http://www.alfredforum.com/topic/3548-php-based-workflow-first-execution-after-some-time-is-slow/

I believe this pull request will help to fix the problem where execution is slow for first time use (after a period of time like one hour)