Update installer.nsi

closes #944
Rewritten nsi script

- overhaul readability by reorganizing content
- hide details when installing/uninstalling, users can click on "view more" if they want to
- File Description now prints "Popcorn Time Setup", because it's what it is.
- unchecked the "launch popcorn time" box by default at the end of the installation
- modified link to website to URL, for internationalization ("Official Homepage" is English, while URL "http://something.io" is international)
- removed unecessary line for coloring background of displayed License.txt
- added all languages supported by NSIS (except Georgian and ScotsGaelic which displays errors on NSIS 3.0b)
- Installer now acts like an updater if PT was already installed. No more "uninstall previous PT before installing"
- exclude "example(s)" folders from "src"
- exclude .md files since they are useless but keeps LICENSE for each node_module, so we're good.
- exclude `*.*~` from the installer since those are backups for some *nix text-editors
- renamed Popcorn-Time.ico to app.ico for readability of the installed directory
- renamed Popcorn-Time.exe to nw.exe
- renamed "Start Popcorn Time" shortcut to "Popcorn Time" for internationalization
- renamed "Start Popcorn Time" start-menu shortcut to "Popcorn Time" for internationalization
- renamed "Uninstall" start-menu shortcut to "Uninstall Popcorn Time" to allow the search for "Popcorn Time" to display the uninstaller
- modified default reg-key to "Popcorn Time" instead of "Popcorn-Time" to fit with the whole project

-> Now the only "Popcorn Time" we can see is the launcher shortcut. Not 4 "Popcorn Time" iterance inside the installed directory
-> Set installation default to ProgramFiles (and use admin privileges) is the way windows program are installed, and PT should follow that. As it should eventually one day follow it also on Linux. For non-admin users, 7zip can extract the installer and the user can build its own directory. Plus, this shouldn't be an issue for update since updater.nsi disappeared and the whole installer needs to be used every time.