reduce fingerprints len by 32.5% to reduce descriptors size
I have read proposals to reduce descriptor size and found fingerprints use SHA1, why not use base64 for them to change for example:
moria relay:
SHA1:
```
string(40) "9695DFC35FFEB861329B9F1AB04C46397020CE31"
```
base64 without trailing padding:
```
string(27) "lpXfw1/+uGEym58asExGOXAgzjE"
```
pseudocode for example:
```
substr(base64_encode(hex2bin('9695DFC35FFEB861329B9F1AB04C46397020CE31')),0,27)
```
results into 32.5% less fingerprints stringlen.
issue