An error occurred while installing curb (0.8.5)
It says it can't install curb gem. Go to curb homepage and check installation section:
On Ubuntu, the dependencies can be satisfied by installing the following packages:
$ sudo apt-get install libcurl3 libcurl3-gnutls libcurl4-openssl-dev
On RedHat:
$ sudo yum install ruby-devel libcurl-devel openssl-devel