improved exception handler, flag to keep unreferenced files

[Diullei]

This PR add the following features:

A flag to keep unreferenced typings when running reinstall command

• Now we can use --keep-unreferenced flag with reinstall command to keep unreferenced files. Regression in 0.6.3 #179

Example:

tsd reinstall --config my-custom-tsd-json --keep-unreferenced

The exception handler has been improved

• Now always we have an exception a log file named tsd-debug.log will be created. This file follows the npm npm-debug.log file concept. Now we can attach this file to submit with an issue always we have an exception. This file will be something like this:

Example:

Trying to use tsd with the command tsd query jquery without an internet connection I got an error like this:

[ERR!] cwd  : /home/.../tsd
[ERR!] os   : Linux 3.19.0-21-generic
[ERR!] argv : "node" ".../build/cli.js" "query" "jquery"
[ERR!] node : v0.12.4
[ERR!] tsd  : 0.6.3
[ERR!] Error: getaddrinfo EAI_AGAIN
[ERR!] CODE : EAI_AGAIN
[ERR!] getaddrinfo EAI_AGAIN
This is most likely not a problem with tsd itself
and is related to network connectivity.
In most cases you are behind a proxy or have bad network settings.

If you are behind a proxy, please make sure that the
'proxy' config is set properly.  See: https://github.com/DefinitelyTyped/tsd#tsdrc
[ERR!] .tsdrc could not be retrieved

[ERR!] Please include the following file with any support request:
    /tsd-debug.log

• Now we have a friendly error message when the GitHub API rate-limit is reached. Handle the Github API 403 error with a friendly message. #178

[ERR!] GitHub API: GitHub rate limit reached.
    To increase the limit use GitHub authentication.
    See: https://github.com/DefinitelyTyped/tsd#tsdrc