use ag-executable instead of literal "ag" in *-dired-* commands
Merge pull request #53 from philsnow/master

use ag-executable instead of literal "ag" in *-dired-* commands
Align the size-column in the dired printout
Merge pull request #55 from Fuco1/align-size-col

Align the size-column in the dired printout
Run the dired-after/before-readin-hook(s)
Merge pull request #54 from Fuco1/run-hooks

Run the dired-after-readin-hook after the ag process is finished