[FEATURE] vault client: create encrypted blob decrypt key if missing

if the key is missing, upon login the key will be automatically
generated and saved to the blobvault.
[FIX] vault-test: increase entropy from randomBytes

When running vault-test.js alone, the entropy was insufficient
for the seed generator.  Entropy must be added elsewhere when
the full test suite is run.
[FIX] vault client: account registration using lowercase version of username

also added username validation with rules from ripple trade client
[CHORE] RippleTxt and AuthInfo changed from classes to objects

fix vault test entropy issue
refactor missing feilds on login
[FEATURE] RippleTxt: parse ripple.txt for currencies
[CHORE] RippleTxt: add tests for new functions
[FIX] blob: catch missing encrypted blob decrypt key
Merge pull request #102 from shekenahglory/develop

Save encrypted blob decrypt key at login if missing