GPM not functioning

I am unable to use any GPM commands to install admin panel or other stuff.
I also believe I have installed all dependencies,

php -v output is as follows:
PHP 5.5.9-1ubuntu4.14 (cli) (built: Oct 28 2015 01:34:46)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies

curl -V output:
curl 7.35.0 (x86_64-pc-linux-gnu) libcurl/7.35.0 OpenSSL/1.0.1f zlib/1.2.8 libidn/1.28 librtmp/2.3
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp smtp smtps telnet tftp
Features: AsynchDNS GSS-Negotiate IDN IPv6 Largefile NTLM NTLM_WB SSL libz TLS-SRP

One potential issue might be the fact i am using internet from behind my institute proxy server.
Does proxy server affect GPM in some way? Does it need to be configured for proxy?

If you are behind a proxy server and this is not a transparent proxy, then yes you need to configure Grav so it knows how to route the requests through the proxy server.

You will probably need to enter a value in your user/config/system.yaml file like this:

proxy_url: your.proxy.com:3125

with the DNS name/IP and port of the proxy server.

If your proxy requires authentication, try this PR I have in the queue: https://github.com/getgrav/grav/pull/698

Cool, thanks for that :)