Several static-content pages

Some of our pages are trivially filled with static text. These can be combined in a single package, or go into the thaliawebsite package. Consider if flatpages is a good idea, whether we want to roll our own, or simply hardcode the relevant content in template files.

Relevant pages;

• Contact
• 'Become a member' (although potentially part of the members app)
• Sister associations
• 'Become an active member' (although potentially part of the active members app)