Updates the formula to no longer rely on deprecated plist functionality.
Fixes the issue with the service failing due to hardcoded PATH variable
for the service. Generates the service manifest dynamically instead of
embedding it into the formula.

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

- Restored --HEAD functionality
- Restored behavior to make sure script runs for each profile
- Restored run-at-load behavior
- Swapped out egrep for regular grep for better portability
- Changed log path to include the plist name like before

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>

Signed-off-by: Ismayil Mirzali <ismayilmirzeli@gmail.com>