Use a dependency manager to handle external packages

[arush-sal]

We have the following external packages imported in the code:

import (
    ...
    “github.com/spf13/cobra”
    “github.com/spf13/viper”
)

Now everyone who wishes to build the code will have to import these packages individually which could become a challenge as the project size and the number of imported packages increases. Therefore we should use a package manager(recommended godep) to take care of this problem. So that the users will just have to issue a single command i.e dep ensure to get all the external packages and they will be all good to build the code.