replaced version 0.12 with 0.13
removed about Macports
added how to install by GVM
tweaked quickstart
added requirements and using groovyserv-setup-nativeclient to howtobuild.rst
tweaked index.rst
added a replacement to native client after installing by gvm to howtoinstall.rst
fixed a text of link anchor in downloads.rst
tweaked quickstart.rst (quoated command name with backquotes)
updated userguide
added about GROOVYSERVER_HOST to userguide
added changelogs of 0.13