make linux .zip package more usable

[nerdCopter]

• the .zip package contains a .desktop launcher; however, it points wrongly to an installation folder /opt/emuflight-configurator by default. therefore if a user launches it, they are really launching an installed verison if it exists.
• this fixes such to include emuflight-configurator-localfolder.desktop pointing to launch the local folders executable.
• this also renames emuflight-configurator.desktop to emuflight-configurator-installed.desktop to avoid further confusion.
• gulpfile required modification to correctly process the rename.

edit:

• unsure if i really like this, but works.

[nerdCopter]

i did this because i found myself manually editing the linux .zip files for every dev-unstable build.