Added support for Samsung Galaxy S4 (#207)

Added support for the Samsung Galaxy S4.

@keith101786 if you are comfortable with it, please test this config.

resolves #196

README.md

@@ -80,7 +80,8 @@ Samsung | Galaxy A7 2016 | a7xelte | | tested
 Samsung | Galaxy A7 2017 | [a7y17lte](https://wiki.lineageos.org/devices/a7y17lte) | | untested
 Samsung | Galaxy Grand Prime VE | grandprimevelte | SM-G531F | tested
 Samsung | Galaxy S III Neo | s3ve3g | GT-I9301I | tested
-Samsung | Galaxy Tab S2 | [gts210vewifi](https://wiki.lineageos.org/devices/gts210vewifi/) | T813 | tested
+Samsung | Galaxy Tab S2 | [gts210vewifi](https://wiki.lineageos.org/devices/gts210vewifi) | T813 | tested
+Samsung | Galaxy S4 | [jfltexx](https://wiki.lineageos.org/devices/jfltexx) | | untested
 Samsung | Galaxy S4 Mini LTE| [serranoltexx](https://wiki.lineageos.org/devices/serranoltexx) | | tested
 Samsung | Galaxy S5 | [klte](https://wiki.lineageos.org/devices/klte) | G900F/M/R4/R7/T/V/W8 | tested
 Samsung | Galaxy S6 | [zerofltexx](https://wiki.lineageos.org/devices/zerofltexx) | | tested

openandroidinstaller/assets/configs/jfltexx.yaml

@@ -0,0 +1,32 @@
+metadata:
+  maintainer: MagicLike
+  device_name: Samsung Galaxy S4 #(Qualcomm)
+  is_ab_device: false
+  device_code: jfltexx
+  supported_device_codes:
+    - jfltexx
+    - jflte
+    - jfltetmo
+  twrp-link: jflte
+  untested: true
+requirements:
+  android: 5.0.1
+steps:
+  unlock_bootloader:
+  boot_recovery:
+    - type: call_button
+      content: >
+        As a first step, you need to boot into the bootloader. A bootloader is the piece of software, 
+        that tells your phone who to start and run an operating system (like Android). Your device should be turned on. 
+        Then press 'Confirm and run' to reboot into the bootloader. Continue once it's done.
+      command: adb_reboot_download
+    - type: call_button
+      content: >
+        In this step, you need to flash a custom recovery on your device. Press 'Confirm and run' to start the process. Confirm afterwards to continue.
+      command: heimdall_flash_recovery
+    - type: confirm_button
+      img: samsung-buttons.png
+      content: >
+        Unplug the USB cable from your device. Then manually reboot into recovery by pressing the *Volume Down* + *Power buttons* for 8~10 seconds 
+        until the screen turns black & release the buttons immediately when it does, then boot to recovery with the device powered off, 
+        hold *Volume Up* + *Home* + *Power button*.