change license to MPL
better virtualbox version checking to make Mac happy
fix the problem with sed silent option in Mac
fix the problem with sed options
MPL in man as well
added a mandatory in BSD sed suffix for the in-place option - closes #44
checks whether there is no arguments for vbkick - needed for bash 3 - fixes #49
add needed prefix to the mktemp to make a Mac OS X happy - related to #47
make sed POSIX compliance - related to #46

use [[:space:]] instead of \s
make grep POSIX compliance

use [[:space:]] instead of \s
use Basic Regular Expressions - BRE for sed and grep - related to #44

use BRE increase portability, special for sed
 where there a different option to turn on Extended Regular Expressions
 for the GNU sed (-r) and the BSD sed (-E).
 POSIX does not mean always portability,
 so that try reduce whitespace characters to spaces [ ] instead of [[:spaces:]] or [[:blank:]] (NB. tested on smartOS)
don't overwrite empty file during VBOX_VERSION autoupdate
make sure that history expansion is turned off
info about gmake
md5 as a default checksum type
added VBOX_MANAGE_PATH env variable to allow change path to the VBoxManage binary
added comment about openssl - always return 0 as a status code, even command fail
update examples
added curl smart installer
update docs