Fix buttons that are without function in Firefox

[probonopd]

Compiled as outlined here.

Clicking on left-hand menu -> ESPmanager goes to ESP Manager, General Settings page.
Clicking on right-hand menu -> Reboot does nothing.

But using curl --data "restart" http://192.168.0.17/espman/data.esp does cause a reboot.

[probonopd]

Working now, had to re-upload the files from the master branch to SPIFFS using https://github.com/esp8266/arduino-esp8266fs-plugin

[probonopd]

The "Save" button still seems to be without function though.

[probonopd]

Moreover, some buttons are not shown at all on Mozilla Firefox 45 on Linux (e.g., the "Submit" button on the ESP Manager start page). Also the Device Name text box is missing on Firefox.