remove Tahoe-related code

Tahoe is gone. This just crudely, removes all the code that
involved tahoe. The only bits left are a couple things in the templates
so we can still view 'tahoe' files, and the stats page so
we can still see the tahoe usage graph.
Merge pull request #12 from zmustapha/ui-enhancements

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Merge pull request #11 from ccnmtl/tahoe-removal

remove Tahoe-related code
another path that shouldn't be hard-coded
* fixing css include for the admin login.
* adding myself as an admin
Remove TAHOE_BASE from config vars, add BROKER_URL
Merge pull request #13 from ccnmtl/eliminate-hardcoded-image-url

another path that shouldn't be hard-coded
Merge pull request #14 from ccnmtl/fix-admin-login

* fixing css include for the admin login.
Merge pull request #15 from nikolas/readme-var-update

Remove TAHOE_BASE from config vars, add BROKER_URL
add TMP_DIR in settings_shared
add a contributing document. closes #16
Merge pull request #17 from djredhand/master

add TMP_DIR in settings_shared
update jQuery to fix debug toolbar

Also updates jquery-ui so the modals show up correctly
include the sequence diagram here so we don't lose it
Merge pull request #18 from nikolas/update-jquery

update jQuery to fix debug toolbar
removed the extra space above the banner in surelink and file