refactor: bash scripts [stip travis]

- shellchecke and shfmt checked and formatted
- indentation 2 spaces
- redirect errors to stderr
- short if where possible
- add function string to clarify visuaally identify its a funtion
- make [ ... ] to [[ ... ]]
- use == for comparision
- use cat based notes
- remove unecessary spaces
- double quotes where needed

build/erpnext-nginx/install_app.sh

@@ -9,7 +9,7 @@ FRAPPE_BRANCH=${4}
 
 mkdir -p /home/frappe/frappe-bench/sites/assets
 cd /home/frappe/frappe-bench
-echo -e "frappe\n${APP_NAME}" > /home/frappe/frappe-bench/sites/apps.txt
+echo -ne "frappe\n${APP_NAME}" >/home/frappe/frappe-bench/sites/apps.txt
 
 mkdir -p apps
 cd apps
@@ -36,8 +36,8 @@ mkdir -p /home/frappe/frappe-bench/sites/assets/${APP_NAME}
 cp -R /home/frappe/frappe-bench/apps/${APP_NAME}/${APP_NAME}/public/* /home/frappe/frappe-bench/sites/assets/${APP_NAME}
 
 # Add frappe and all the apps available under in frappe-bench here
-echo "rsync -a --delete /var/www/html/assets/frappe /assets" > /rsync
-echo "rsync -a --delete /var/www/html/assets/${APP_NAME} /assets" >> /rsync
+echo "rsync -a --delete /var/www/html/assets/frappe /assets" >/rsync
+echo "rsync -a --delete /var/www/html/assets/${APP_NAME} /assets" >>/rsync
 chmod +x /rsync
 
 rm /home/frappe/frappe-bench/sites/apps.txt