dump_devinfo improvements (#657)

* dump_devinfo improvements

* Scrub only the last three bytes for mac addresses
* Add --target to allow creating fixtures based on discovery
* Save fixtures directly to correct location, add --basedir to allow defining the location of repository root
* Add --autosave to disable prompting for saving

* Update fixtures for devices I have

* Add fixture for HS110 hw 4.0 fw 1.0.4

* Improve help strings

* Fix tests

* Update devtools README

* Default to discovery if no host/target given

kasa/tests/fixtures/HS110(EU)_1.0_1.2.5.json

@@ -1,44 +1,32 @@
 {
     "emeter": {
         "get_realtime": {
-            "current": 0.015342,
+            "current": 0.014937,
             "err_code": 0,
-            "power": 0.983971,
-            "total": 32.448,
-            "voltage": 235.595234
+            "power": 0.928511,
+            "total": 55.139,
+            "voltage": 231.067823
         }
     },
-    "smartlife.iot.common.emeter": {
-        "err_code": -1,
-        "err_msg": "module not support"
-    },
-    "smartlife.iot.dimmer": {
-        "err_code": -1,
-        "err_msg": "module not support"
-    },
-    "smartlife.iot.smartbulb.lightingservice": {
-        "err_code": -1,
-        "err_msg": "module not support"
-    },
     "system": {
         "get_sysinfo": {
             "active_mode": "schedule",
             "alias": "Kitchen",
             "dev_name": "Wi-Fi Smart Plug With Energy Monitoring",
-            "deviceId": "8006588E50AD389303FF31AB6302907A17442F16",
+            "deviceId": "0000000000000000000000000000000000000000",
             "err_code": 0,
             "feature": "TIM:ENE",
             "fwId": "00000000000000000000000000000000",
-            "hwId": "45E29DA8382494D2E82688B52A0B2EB5",
+            "hwId": "00000000000000000000000000000000",
             "hw_ver": "1.0",
             "icon_hash": "",
-            "latitude": 51.476938,
+            "latitude": 0,
             "led_off": 1,
-            "longitude": 7.216849,
-            "mac": "50:C7:BF:01:F8:CD",
+            "longitude": 0,
+            "mac": "50:C7:BF:00:00:00",
             "model": "HS110(EU)",
-            "oemId": "3D341ECE302C0642C99E31CE2430544B",
-            "on_time": 512874,
+            "oemId": "00000000000000000000000000000000",
+            "on_time": 6023162,
             "relay_state": 1,
             "rssi": -71,
             "sw_ver": "1.2.5 Build 171213 Rel.101523",