fixed the sid truncation issue and added tests for it, fixes #373
shuffled around the test a bit to make it clearer
it doesn't matter what ind you pass in, since it is always recalcuated so the parameter can be removed
simplifed insert_sid to actually parse the query string, modify the sid, and then encode the querystring again
ILLIAD_SID is configurable and may be longer (or shorter) than 4 characters
insert_sid should still return a url when a url does not have a sid
minor update, refs #373
minor changes to tests.py, refs #373
added functionality to fix improperly encoded ampersands in parameter values
few more docs, and relax parsing of query string after fixing ampersands in case there are other problems
Merge pull request #388 from gwu-libraries/t373-sid-truncation-when-dbname-includes-

fixed the sid truncation issue and added tests for it, fixes #373