Add getting known php version online

running `phpbrew known` can get the lastest php version.

Signed-off-by: Yi-Feng Tzeng <yftzeng@gmail.com>
Merge pull request #11 from yftzeng/features-add-get-phpvesion-online

Add getting known php version online
Update phar file
Fix bug: pdo_pgsql variant
bump version for bug fix
compile new phar file
Update package.xml
enable --enable-calendar by default.
Add release.sh script
Release
Update readme
Improve extension-installer
Add posix variant
Update changes.md
Release
Fix current php dir
Release
Fix install-ext command
bump version for bug fix
bump class version for bug fix