feat(info): Show index and bloom filter size

[jarifibrahim]

This PR depends upon dgraph-io/ristretto#197
badger info now shows index size and bloom filter size

>badger info --dir xxx --show-tables
SSTable [L3, 204, 0450361] [    00000000046B8156, v1 ->     000000000472608E, v1] [433 kB] [1.0 MB] 
SSTable [L3, 205, 0450360] [    00000000011132C7, v1 ->     00000000011811FE, v1] [433 kB] [1.0 MB] 
SSTable [L3, 206, 0450360] [    00000000028EAB05, v1 ->     0000000002958A3C, v1] [433 kB] [1.0 MB] 
SSTable [L3, 207, 0450361] [    0000000003ACC537, v1 ->     0000000003B3A46F, v1] [433 kB] [1.0 MB] 
SSTable [L3, 208, 0450361] [    0000000005E8F995, v1 ->     0000000005EFD8CD, v1] [433 kB] [1.0 MB] 
SSTable [L3, 209, 0395313] [    000000000472608F, v1 ->     00000000047868BF, v1] [380 kB] [524 kB] 
SSTable [L3, 210, 0395313] [    00000000011811FF, v1 ->     00000000011E1A2F, v1] [380 kB] [524 kB] 

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This change is 

[martinmr]

Reviewed 3 of 3 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ashish-goswami and @manishrjain)

[manishrjain]

Reviewed 3 of 3 files at r1, 2 of 2 files at r2.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @ashish-goswami and @jarifibrahim)

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badger/cmd/info.go, line 253 at r2 (raw file):

		fmt.Printf("SSTable [L%d, %03d, %07d] [%20X, v%d -> %20X, v%d] [%s] [%s] \n",
			t.Level, t.ID, t.KeyCount, lk, lt, rk, rt, hbytes(int64(t.IndexSz)), hbytes(int64(t.BfSize)))

100 chars.

Also sum it up and print the total index size.

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table/table.go, line 659 at r2 (raw file):

// BFSize returns the size of the bloom filter in bytes stored in memory. The
// size of on-disk representation would be less than the in-memory representation.
func (t *Table) BFSize() int {

BloomFilterSize()