avoid redundant searches to get root namingcontexts when no basedn is set
make grab method private since it's only used internally
fetch group uids on demand
Revert "fetch group uids on demand"

This reverts commit 6232d5ea5c76cd965e9ca079d6525848b7b78bfe.
raise an error if we try to perform concurrent searches on an open LDAP connection since that can cause unexpected results
correct spec description
only fetch group uids and managers if/when we know we need them
simplify by having the fetch* methods set the instance vars
cache groups and managers between calls
bump version
don't set @search_in_progress to false if the error is rescued
Merge pull request #45 from socialcast/cache-groups-and-manager

Cache groups and manager