distinct URI for suspend/delete

/users/?suspend=<username>  =>  /users/suspend/<username>
/users/?delete=<username>   =>  /users/delete/<username>
added possibility to delete users
added granting/revoking of admin privileges

any admin (username 'admin' or account_type 'admin') can toggle the
account_type of any other non-guest user from 'admin' to 'user' and vice-versa
the "real" admin (username 'admin') is of course unaffected
Merge branch 'master' into usermgmt
Merge branch 'master' into usermgmt
Merge branch 'master' into usermgmt
Merge branch 'master' into usermgmt
Merge branch 'master' into usermgmt
Update sagenb/notebook/notebook.py

Add Fricas as one of the SYSTEMS options.
Merge branch 'master' into usermgmt
Merge branch 'master' into usermgmt
sage.misc.latex_macros: do not evaluate anything on startup. See trac #13504
With introspection and live documentation in the notebook, fix spurious \(,\) and \[,\] pairs
Fix introspection and live documentation in the notebook
mmarco's idea to solve "invalid username" error

Trac 13536 - password recovery does not work.
This is mmarco's patch for fixing it.
create default users if "admin" doesn't exist
jQuery reference repair in graph_editor
Merge pull request #104 from lukas-lansky/graph-editor-jQuery

jQuery reference repair in graph_editor
Merge pull request #101 from rmartinjak/issue-47

create default users if "admin" doesn't exist
Merge branch 'master' into usermgmt