Change http to https, make installation of glog, gflags and double-conversion consistent; use github url for double-conversion

To fix the error:

sudo: apt-get: command not found
fetching glog from svn (apt-get fails)
svn: E175002: Unable to connect to a repository at URL 'http://google-glog.googlecode.com/svn/trunk'
svn: E175002: OPTIONS of 'http://google-glog.googlecode.com/svn/trunk': Could not read status line: connection was closed by server (http://google-glog.googlecode.com)