Include Welcome Screen on Engine srcd init

[ricardobaeta]

After srcd init I would love to be welcomed and guided. If I'm on the cli, I don't want to switch to the docs to know how to move forward, and most importantly I want to quickly know how can I get the most of the Engine, so I would be pretty much happy to have a continuous experience.

We now get:

starting daemon with working directory: /Users/ricardobaeta/Library/Mobile Documents/com~apple~CloudDocs/source{d}/gopath/src/github.com 

So, how would it be having no need for context change? I propose we add the following to this output: (this should be so much better)

starting daemon with working directory: /Users/ricardobaeta/Library/Mobile Documents/com~apple~CloudDocs/source{d}/gopath/src/github.com

~~~~ Welcome to source{d} Engine ~~~~

Quick Start to turn your code into actionable insights.

Commands:
srcd sql                   Run a SQL query over the analyzed repositories - cli mode
srcd web sql           Run a SQL query over the analyzed repositories - web mode
srcd parse               Classify languages, parse files, and manage parsers - cli mode
srcd web parse       Classify languages, parse files, and manage parsers - web mode
srcd status              Comprehensive Report of your Installation Setup

Examples:
srcd sql                   select * from repositoris; - cli mode
srcd web sql           Top languages by repository count - web mode
srcd parse               srcd parse uast /path/to/file.java - cli mode
srcd web parse       Load raw gist url and run parser - web mode

Help:
srcd -h
srcd sql --help
srcd parse --help