fix proxy error for activate and terminate app

[KazuCocoa]

Fix the following proxy error for terminate_app and activate_app

[HTTP] --> POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/terminate_app {"appId":"io.appium.android.apis"}
[W3C] Driver proxy active, passing request on via HTTP proxy
[debug] [JSONWP Proxy] Proxying [POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/terminate_app] to [POST http://localhost:8200/wd/hub/session/328f5c81-65c3-41dd-9c8b-ad819dbf29fc/appium/device/terminate_app] with body: {"appId":"io.appium.android.apis"}
[W3C] Encountered internal error running command: Error: Could not proxy. Proxy error: Could not proxy command to remote server. Original error: 404 - undefined
    at doJwpProxy$ (/Users/kazuaki/GitHub/appium/node_modules/appium-base-driver/lib/protocol/protocol.js:404:13)
    at tryCatch (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:67:40)
    at GeneratorFunctionPrototype.invoke [as _invoke] (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:315:22)
    at GeneratorFunctionPrototype.prototype.(anonymous function) [as throw] (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:100:21)
    at GeneratorFunctionPrototype.invoke (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:136:37)
    at <anonymous>
[HTTP] <-- POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/terminate_app 500 49 ms - 1315
[HTTP] --> POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/activate_app {"bundleId":"io.appium.android.apis"}
[W3C] Driver proxy active, passing request on via HTTP proxy
[debug] [JSONWP Proxy] Proxying [POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/activate_app] to [POST http://localhost:8200/wd/hub/session/328f5c81-65c3-41dd-9c8b-ad819dbf29fc/appium/device/activate_app] with body: {"bundleId":"io.appium.android.apis"}
[W3C] Encountered internal error running command: Error: Could not proxy. Proxy error: Could not proxy command to remote server. Original error: 404 - undefined
    at doJwpProxy$ (/Users/kazuaki/GitHub/appium/node_modules/appium-base-driver/lib/protocol/protocol.js:404:13)
    at tryCatch (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:67:40)
    at GeneratorFunctionPrototype.invoke [as _invoke] (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:315:22)
    at GeneratorFunctionPrototype.prototype.(anonymous function) [as throw] (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:100:21)
    at GeneratorFunctionPrototype.invoke (/Users/kazuaki/GitHub/appium/node_modules/babel-runtime/regenerator/runtime.js:136:37)
    at <anonymous>
[HTTP] <-- POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/activate_app 500 15 ms - 1315
[HTTP] --> POST /wd/hub/session/c579c9fc-32cc-49b8-9dc5-3ad46c4fe80f/appium/device/app_installed {"bundleId":"io.appium.android.apis"}
[debug] [W3

appium/ruby_lib_core#58

[mykola-mokhnach]

There is also app_state endpoint.
Here's the whole list /~https://github.com/appium/appium-base-driver/blob/2933fe45ecead1283f13825c0e64e799bfabd2ba/lib/protocol/routes.js#L401