EP: misc fixes (#38)

* `@0x/contracts-zero-ex`: Fix NativeOrdersFeature order hash cancellation not emitting proper maker.
`@0x/contracts-zero-ex`: Revert to original (deployed) ZeroEx/EP proxy implementation. Optimized one is now at `ZeroExOptimized.sol`.
`@0x/contracts-zero-ex`: Add gas limits to first `transferFrom()` call in `LibTokenSpender` and `UniswapFeature`.

* `@0x/contracts-zero-ex`: Update changelog

* disable `no-empty-blocks` solidity linter rule

* `@0x/contracts-zero-ex`: Use bloom filters of greedy tokens in token transfer logic
`@0x/contracts-zero-ex`: Turn `LibTokenSpender` into `FixinTokenSpender`.
`@0x/contracts-zero-ex`: Misc renames for consistency.

* `@0x/contracts-zero-ex`: Export `GREEDY_TOKENS` list

* rebase and update changelog

* `@0x/contracts-zero-ex`: Change bloom filter hash algo based on discussions

* `@0x/contracts-zero-ex`: Fix changelog

* update orders docs

* `@0x/contracts-zero-ex`: revert if allowance call fails in uniswap feature

Co-authored-by: Lawrence Forman <me@merklejerk.com>

contracts/zero-ex/src/constants.ts

@@ -0,0 +1,21 @@
+export const ZERO_BYTES32 = '0x0000000000000000000000000000000000000000000000000000000000000000';
+
+// List of tokens that consume all gas when they fail.
+export const GREEDY_TOKENS = [
+    // USDT
+    '0xdac17f958d2ee523a2206206994597c13d831ec7',
+    // LINK
+    '0x514910771af9ca656af840dff83e8264ecf986ca',
+    // ORAI
+    '0x4c11249814f11b9346808179cf06e71ac328c1b5',
+    // BNT
+    '0x1f573d6fb3f13d689ff844b4ce37794d79a7ff1c',
+    // LIT
+    '0x763fa6806e1acf68130d2d0f0df754c93cc546b2',
+    // KNC
+    '0xdd974d5c2e2928dea5f71b9825b8b646686bd200',
+    // DIP
+    '0xc719d010b63e5bbf2c0551872cd5316ed26acd83',
+    // MINI
+    '0x4d953cf077c0c95ba090226e59a18fcf97db44ec',
+];