Pin errorprone version and thus javac version

[vprithvi]

• The errorprone plugin pulls in the latest version of errorprone which
  replaces javac with a dev build of JDK9.
  JDK9 dev builds don't play well with lombok.
  This commit updates lombok/errorprone plugins and pins errorprone to a
  version that builds correctly

[codecov-io]

Codecov Report

Merging #128 into master will increase coverage by 0.05%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master     #128      +/-   ##
============================================
+ Coverage     81.11%   81.16%   +0.05%     
- Complexity      497      498       +1     
============================================
  Files            89       89              
  Lines          1885     1885              
  Branches        181      181              
============================================
+ Hits           1529     1530       +1     
  Misses          268      268              
+ Partials         88       87       -1

Impacted Files	Coverage Δ	Complexity Δ
.../uber/jaeger/samplers/RemoteControlledSampler.java	92.85% <0%> (+1.42%)	19% <0%> (+1%)	✅

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