Set Recommended/Default Collateral Ratio to At Least 5 to Avoid Newbie Get Burned Easily

**Is your feature request related to a problem? Please describe.**
Newbie who borrow bitCNY/bitUSD get burned easily because they are more likely to set 1.75 Collateral Ratio until they get margin call. Once they get margin call, they will either become conservative or stop borrow bitCNY/bitUSD. If they stop borrow bitCNY/bitUSD, then is not good for Bitshares.

**Describe the solution you'd like**
1. Set recommended/default Collateral Ratio to At Least 5.
2. Description should encourage borrowers set Collateral Ratio of 5 and above.

Start by locating the collateral-ratio control and its accompanying description in the wallet UI. Verify where the default or recommended value is defined, then confirm that the interface uses at least 5 and encourages borrowers to choose 5 or above.

Written by the indexing model from the issue text.