Fix liquidity price conversion and fees calculation

[benber86]

Fix 1: The values displayed on the user account chart for liquidity on specific pools were equal to avax_amount * avax_price * avax_price instead of just avax_amonut * avax_price due to a race condition (#13). This fixes it

Fix 2: This is for an issue originally raised on Uniswap. The Pangolin code is the same so the issue is also present here.
If an account is the first to provide liquidity on a pair, the calculation of their ownership of the pool when they entered it will return a NaN because it will try to divide by a liquidityTokenTotalSupply that is equal to 0. The ownership NaN at t0 will then affect all subsequent calculations, including the sum of fees. Consequently the fees will not be displayed on the interface. Note: this should not affect #14 on which another user is currently working.

[bmino]

Am I missing something @benber86? This should fix #13

[benber86]

apologies for bad formatting and bad communication, the note was copypasted from 1716d74 and only applied to it. 79ac297 should indeed fix #13
I'll edit the comment

[dasconnor]

Great work!