Investigate fcrepo jsessionid cache issue

[UcDust]

It appears the JSESSIONID cookie can expire in the browser and cause issues with PUT requests into fcrepo. For the DAMS project, this results in 403 Forbidden errors when trying to save admin data into /application/ucd-lib-client/.

As a work around, in the fin gateway proxy model, during proxy requests we're deleting the cookie header, and in the login authentication success callback we're setting a new JSESSIONID header.

It might be worth investigating in more detail how fcrepo is using this cookie, and perhaps handle things differently in our code.

[UcDust]

The changes described above can be seen in this commit.