Custom image functionality (MIFOSX-1160)

Ignore the first four commits (I was creating and deleting an image)

This contribution adds functionality to add a custom logo to the MifosX client.  A user would put his or her custom image in the images directory, with the name "custom_logoSmall.png"

Details here:
https://mifosforge.jira.com/browse/MIFOSX-1160