feat(install): Add automatic logs to install script (#312)

This change makes the install script create a new install log file, `sentry_install_log-<ISO_TIMESTAMP>.txt`, for each run and records all the output there for future reference.

install.sh

@@ -1,6 +1,10 @@
 #!/usr/bin/env bash
 set -e
 
+# Thanks to https://unix.stackexchange.com/a/145654/108960
+log_file="sentry_install_log-`date +'%Y-%m-%d_%H-%M-%S'`.txt"
+exec &> >(tee -a "$log_file")
+
 MIN_DOCKER_VERSION='17.05.0'
 MIN_COMPOSE_VERSION='1.19.0'
 MIN_RAM=2400 # MB