[AC-5560] Android: Ti.identity failure to encrypt the data with the generated key.

In Ti.identity module, there is an additional step after a fingerprint validation success, which is to try to encrypt some data with the generated key in createKey method . [See onAuthenticationSucceeded method in FingerPrintHelper.java](https://github.com/azamouchi/titanium-identity/blob/63e0bd48d234b6211095007dd0750da9bf840d8c/android/src/ti/identity/FingerPrintHelper.java#L149) [See tryEncrypt method in FingerPrintHelper.java](https://github.com/azamouchi/titanium-identity/blob/63e0bd48d234b6211095007dd0750da9bf840d8c/android/src/ti/identity/FingerPrintHelper.java#L118) The problem is, on some android devices running Android 6.0 the encryption of the data with the previously generated key raise an exception, which leads to fails the authentification. As mentioned in this [stackOverflow thread](https://stackoverflow.com/questions/36043912/error-after-fingerprint-touched-on-samsung-phones-android-security-keystoreexce), the problem seems to be encountered randomly on some android devices running Android 6 like Samsung, OnPlus, in my case i face the problem every time i try to authenticate with [this device](https://www.gsmarena.com/wiko_u_feel_lite-8204.php), which make the fingerprint authentification impossible. My question : Is this encryption step mandatory ? can we make it optional ? since the onAuthenticationSucceeded method has been already called, which means that the fingerprint verification is OK.