Updated shell scripts to be compatible with HTTP Digest authentication

Because curl and wget do not let use a hashed password as parameter,
YaCy shell scripts which require authentication are now interactive by
default when HTTP Digest is the only available authentication method.
Batch mode can still be available trough the use of an environment
variable : YACY_ADMIN_PASSWORD.  

Other improvements :
 - added backward compatibility for Basic Authentication
 - fixed curl/wget presence detection 
 - do not return with exit code 0 when an API call failed, and print an
error message when the case occurs
 - documented available authentication options for API calls

stopYACY.sh

@@ -1,10 +1,11 @@
 #!/usr/bin/env sh
 cd `dirname $0`
 
-bin/apicall.sh "Steering.html?shutdown=true" > /dev/null
+(bin/apicall.sh "Steering.html?shutdown=true" > /dev/null && \
 
-echo "Please wait until the YaCy daemon process terminates [wget]"
-echo "You can monitor this with 'tail -f DATA/LOG/yacy00.log' and 'fuser log/yacy00.log'"
+echo "Please wait until the YaCy daemon process terminates [wget]" && \
+echo "You can monitor this with 'tail -f DATA/LOG/yacy00.log' and 'fuser log/yacy00.log'") || \
+exit $?
 
 # wait until the yacy.running file disappears which means that YaCy has terminated
 # If you don't want to wait, just run this concurrently