#171 responsibility tag

[Aprotim Sanyal]

Add a "responsibilities" and "responsibility" tag for
the job tag, similar to "projects" and "project".

eg:

<responsibilities>
<responsibility>Maintained computers</responsibility>
<responsibility>Kicked puppies</responsibility>
<responsibility>Took candies from
babies</responsibility>
</responsibilities>

could show up as a bulleted list under the job
descripttion:

Responsibilities:
- Maintained computers
- Kicked puppies
- Took candies from babies