win installer check at least for 4gb space. resource observer pauses

crawling at 3gb free space by default and informs user what to do. so
1gb can be used by yacy at full feature. 30gb warning comes quite often
on installation time. users are confused about it and may never reach
it.

build.nsi

@@ -39,7 +39,7 @@ InstallDir "$PROFILE\YaCy"
 InstallDirRegKey HKCU "Software\Microsoft\Windows\CurrentVersion\Uninstall\YaCy" "UninstallString"
 
 ;recommend free space in GB for YaCy
-!define RecommendSpace "30"
+!define RecommendSpace "4"
 
 ; commands for firewall config, see http://support.microsoft.com/kb/947709/en-us
 !define WinXPAddFwRulePort 'netsh firewall add allowedprogram name="YaCy" program="%SystemRoot%\System32\javaw.exe"'