Right-aligned date/time in command history/exec

Changed the command history and command executor templates so that the
date/time is right-aligned.

Before:
![hist_before](https://f.cloud.github.com/assets/432817/2065128/97b7cafc-8cdb-11e3-8f1f-6222656915da.png)

After:
![hist_after](https://f.cloud.github.com/assets/432817/2065129/9d2ba026-8cdb-11e3-87e6-bc9f66729b49.png)