Small wording and naming changes

Summary:
Just some small changes that made the core easier for me to understand as I went through it.

**Test plan (required)**

    $ cd react-native
    # "Install globally" without using Sinopia :)
    $ cp -r react-native-git-upgrade /usr/local/lib/node_modules/

    $ cd ~
    $ react-native init Zero29App --version=0.29.2
    $ cd Zero29App

Made a small change in `MainApplication.java` to introduce a conflict with the new template.

    $ git init && git add . && git commit -m "Initial commit"
    $ react-native-git-upgrade

Worked, printed the conflicting file. Output: http://pastie.org/10972793

    $ git reset --hard
    $ react-native-git-upgrade --verbose

Worked, printed the conflicting file. Output: http://pastie.org/10972796

In both cases (with and without --verbose) the output of `git st` was http://pastie.org/10972795
Closes https://github.com/facebook/react-native/pull/11197

Differential Revision: D4251008

Pulled By: mkonicek

fbshipit-source-id: c5bbbeaf996cb5cb46cccc12fd1da7634cc23520