Fix #1682 by adding some additional validation

We should now report an error when packages containing long URLs are uploaded through the UI.

Fixes #1682 

Also, fixes #1745 by showing the following if minClientVersion is > current client version installed in gallery:

![image](https://f.cloud.github.com/assets/7574/1616992/1086c60c-5615-11e3-99cb-d42f66d889a7.png)