fix: don’t block forever in case of connection problems

We set a graceful default socket timeout of 30 seconds so that none of
our connections can block forever.
thread-safety bug fix: use a single lock instead of one per thread
add and activate preliminary versions of the CLARIN EULA templates
Merge pull request #718 from cspurk/various-improvements

(1) don’t block forever in case of connection problems; (2) thread-safety bug fix: use a single lock instead of one per thread; (3) add and activate preliminary versions of the CLARIN EULA templates