Issue title: Custom error message
 Issue body: Hi, i love this lib.
But i cannot custom error message.
My input is number, and errorMessage="Invalid name", but when i type `-` , input always shows default message: This field is invalid
So Could you tell me how do i custom that message. Thank you.
Here is my code https://codesandbox.io/s/damp-snow-w9dxu?file=/src/App.js
![image](https://user-images.githubusercontent.com/12009276/95286750-5cc93300-088e-11eb-843e-7c8036d26b12.png)

 Comments: 
 Comment 0: Hi there! The reason you're seeing `This field is invalid` instead of your custom error message has to do with line 15 where you have `type="number"`. The HTML Number type has some [built in validation](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/number#Validation) that won't allow normal characters to be typed, so in your screenshot the `value` of the component is `""`.

Changing line 15 to be `type="text"` will allow these values and your custom error message will show up based on based on your `pattern`, `minLength`, and `maxLength` validation.
 Comment 1: @chrishavekost  but i just want to allow input number
 Comment 2: Part of this is because of how the browser handles `type="number"` inputs which are invalid. The browser's validation is actually what is running in this case, not this library's validation. The browser never gives value to the library (at least in chrome), even when trying to get the input's value directly, it's an empty string (so we cannot run our own validation). In these cases we have to depend on `target.validity.badInput` to determine if the input is invalid. When that is invalid we don't know which one of our validations would correlate and cannot show specific error messages.

https://github.com/Availity/availity-reactstrap-validation/blob/3d44e388208438134879a30d414fff835a0f4c71/src/AvBaseInput.js#L126
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