Fix unittest that does not pass

[samraul]

• A gasPrice of 0 can't be set with the current version of the libraries
• Gas fee needs to be accounted for
• Flag the fact that the default account balances are too big for JS to properly compute the balance changes

  ✓ can Create a Star (49ms)
  ✓ lets user1 put up their star for sale (53ms)
  ✓ lets user1 get the funds after the sale (100ms)
  ✓ lets user2 buy a star, if it is put up for sale (113ms)
  ✓ lets user2 buy a star and decreases its balance in ether (88ms)
  ✓ can add the star name and star symbol properly
  ✓ lets 2 users exchange stars (126ms)
  ✓ lets a user transfer a star (73ms)
  ✓ lookUptokenIdToStarInfo test (41ms)

  9 passing (668ms)