Make it easier to have custom title and text on page

[yannickwurm]

Many publicly facing sites use SequenceServer as their BLAST mechanism. We currently don't have a good way of people to customise what they show. (the workaround chosen by some is to modify seqserv code... which makes it difficult to update).

Instead, the config file should make it possible to:

• add a custom title
• add a custom description
• add custom text between the search box and the database list
• add custom information to the footer (e.g., information about database name to cite, or data publications).

The extra information should be added to rather than replacing our existing Seqserv information.