More fixes and improvements

(2020-03-31)

Continued bug fixes, performance improvements, and optimizations.

• Add HighestSlotStatesBelow DB getter (#5213) (2df7679), closes #5213
• Add alpine based docker images for validator and beacon chain (#5214) (3792bf6), closes #5214
• Add configurable e2e epochs (#5235) (f89d753), closes #5235
• Add configurations for BLS builds (#5254) (6edb301), closes #5254
• Add Hasher To State Data Types (#5244) (7e50c36), closes #5244
• Add Merkleize With Customized Hasher (#5234) (63df1d0), closes #5234
• Attempt E2E flaking fix (#5256) (404a0f6), closes #5256
• Batch save blocks for initial sync. 80% faster BPS (#5215) (c5f186d), closes #5215
• Check new state mgmt service is compatible with DB (#5231) (c67b01e), closes #5231
• Custom Block HTR (#5219) (cdac3d6), closes #5219
• Faster hashing for attestation pool (#5217) (c4c9a84), closes #5217
• Fix E2E test sharding (#5248) (0982ff1), closes #5248
• Fix save blocks return nil (#5237) (b40e6db), closes #5237
• Handle genesis case for blocks/states at slot index (#5224) (1a0a399), closes #5224
• init-sync revamp (#5148) (7ebb3c1), closes #5148
• is slashable attestation endpoint implementation (#5209) (93e68db), closes #5209
• Micro optimizations on new-state-mgmt service for initial syncing (#5241) (7f7866f), closes #5241
• new fixes (#5221) (4118fa5), closes #5221
• Prevent panic for different size bitlists (#5233) (6bc70e2), closes #5233 #5232
• Productionization new state service part 1 (#5230) (f2a3fad), closes #5230
• Prune garbage state is not for new state mgmt (#5225) (6a4b17f), closes #5225
• Revert "Add Fast Copy of Trie" (#5228) (33f6c22), closes #5228 #5221
• Separate anti flakes to prevent E2E issues (#5238) (cb9ac62), closes #5238
• Short circuit genesis condition for new state mgmt (#5223) (5e2faf1), closes #5223
• Skip anti-flake E2E tests (#5257) (3e81afd), closes #5257
• Uncomment out cold state tests (#5252) (e22365c), closes #5252
• Unmarshal Block instead of State (#5246) (c8f8e3f), closes #5246
• Use math.Sqrt for IntegerSquareRoot (#5253) (17516b6), closes #5253
• Debug: add cgo symbolizer (#5255) (00ef08b), closes #5255
• HashProto: Use fastssz when available (#5218) (a245461), closes #5218