HTTPASYNC-79: Rearranged sequence of operations upon connection lease to eliminate possibility of a connection leak due to race condition on keep-alive boundary

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpasyncclient/trunk@1610617 13f79535-47bb-0310-9956-ffa450edef68
Upgraded HttpClient version to 4.4-alpha1; updated OSGi imports

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpasyncclient/trunk@1610618 13f79535-47bb-0310-9956-ffa450edef68