Increase 512 kbyte limit for `ipfs object put`

[kpcyrd]

For a mirroring project, I'm trying to add very large folders to ipfs (> 10k links).

I've used ipfs object patch add-link for this, but switched to ipfs object put for performance reasons.

Current go-ipfs has a hardcoded limit for ipfs object put, which is 512 kbytes.

The folder I'm trying to add to ipfs is too large for this limit.

[Kubuxu]

@kpcyrd it is more of an issue of ipfs object patch add-link disregardig soft limits we set in go-ipfs. Bigger directories are planned and worked on: ipfs/notes#76

[kpcyrd]

//cc: @whyrusleeping