build: fix librt requirement

The librt is added by the gl m4 macros, AC_CHECK_FUNCS to will not fail
to find functions.

Move the AC_CHECK_FUNCS above gl initialization.

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>
doc update
corrected key ID size check
Added userPrincipalName
print warning when no token name is provided
updated txt
do not specify a default class when searching for objects to delete

This fixed issue when trying to delete all the keys in a token by
using the token URL.