[feat] Provide a testnet ready release of desktop wallet

[franciscom0301]

Expected Behavior

X-Cash testnet is now deployed, however only tech savvy users are able to participate with votes (using wallet-cli). By releasing a testnet version of Desktop wallet, any user from x-cash community would be able to participate and help on testnet.

Current Behavior

Desktop wallet can be connected to testnet node rpc, and it will in fact download testnet blocks. Transfers will work as well. However, when it comes to voting, reserve proofs will always appear as invalid.

Possible Solution

From my perspective, voting process is making use of mainnet seed nodes, so reserve proofs from testnet wont match with mainnet ones. Changing the seed nodes that come predefined on code to testnet ones may solve the issue and accomplish our goal.