Fix installation and uninstall scripts
Fix installation and uninstall scripts

* Currently, the install script is missing the hashbang completely
  and the uninstall script and crowdin link use /bin/sh
* This results in errors on a standard Ubuntu 20.04 installation:

Install:
sudo ./install-crowdin-cli.sh
[sudo] Passwort für michael:
./install-crowdin-cli.sh: 1: [[: not found
Checking JAVA installation...
-p: not found
java is /usr/bin/java
./install-crowdin-cli.sh: 8: [[: not found
Looks like JAVA is not installed. You can download it from https://www.java.com/
./install-crowdin-cli.sh: 14: [[: not found

Deinstall:
sudo /usr/local/bin/crowdin_uninstall
/usr/local/bin/crowdin_uninstall: 2: [[: not found
crowdin-cli uninstalled!

With this change, both installation and deinstallation work flawlessly

crowdin/crowdin-cli,crowdin/crowdin-cli