Committer email in /webhook/git controller

This commit adds the ability of committer email set. 

And `post-receive` git hook will be like this:
```bash
#!/bin/sh

PROJECT_ID=1
PHPCI_URL="http://my.server.com/PHPCI/"

trigger_hook() {
        BRANCH=$(git rev-parse --symbolic --abbrev-ref $3)
        COMMITTER_EMAIL=$(git --no-pager show -s --format='%ae' $2)

        echo "Sending webhook"
        curl "$PHPCI_URL/webhook/git/$PROJECT_ID?branch=$BRANCH&commit=$2&committer_email=$COMMITTER_EMAIL"
}

if [ -n "$1" -a -n "$2" -a -n "$3" ]; then
        PAGER= trigger_hook $1 $2 $3
else
        while read oldrev newrev refname
        do
                trigger_hook $oldrev $newrev $refname
        done
fi
```