Fixed the "offset 'en'" error while updating a setting form which include translate disabled field

[yanhao-li]

Reference: #50
This PR include the following two commits,
The first commit fixed the error happened when update the setting, by improving the setting update strategy.
The second commit changed A17TextField's value render strategy by converting the passed value to a reasonable string, avoid the situation that in some cases, it will display "[object object]", not only in this case, but also may happen elsewhere.

[ifox]

Thanks for this @yanhao-li! As discussed earlier today, another PR got merged which included a fix for this #87. Also see 2570c5f and 8d251f1 for some more related commits.

To avoid displaying [object object] I found a solution in the form field blade file, when the vuex store content is outputted inline, because that's the only part of the code that knows if the developer intend to make the field translatable. Settings should now work in various configurations that weren't supported before 👍

[yanhao-li]

Awesome, Thanks @ifox