Finalized budget proposal collateral should work with multiple inputs

[meyer9]

Describe the issue

Signing the final budget proposal fails if multiple inputs are used. Multiple inputs should be able to be used as collateral for the finalized budget proposal.

Expected behavior

The finalized budget proposal should be able to sign multiple inputs.

Actual behavior

The finalized budget proposal is not able to sign multiple inputs.

Screenshots.

https://cdn.discordapp.com/attachments/434484437322039308/434695482187448321/Screen_Shot_2018-04-14_at_5.41.36_AM.png

What version of Phore Core are you using?

v1.2.1

Machine specs:

• OS: Linux/Mac