fix #218 add predicate based http server compression

[smaldini]

HttpServerBuilder now exposes a compression(BiPredicate<Req,Res>).
The predicate is evaluated before committing response header/status.
If the predicate is true, compression is enabled for the given response.
The minimum compression threshold now uses content-length predicate.

[codecov-io]

Codecov Report

Merging #299 into master will increase coverage by 0.45%.
The diff coverage is 84.21%.

@@             Coverage Diff             @@
##             master    #299      +/-   ##
===========================================
+ Coverage     66.64%   67.1%   +0.45%     
- Complexity     1005    1021      +16     
===========================================
  Files            74      74              
  Lines          4332    4362      +30     
  Branches        615     623       +8     
===========================================
+ Hits           2887    2927      +40     
+ Misses         1075    1064      -11     
- Partials        370     371       +1

Impacted Files	Coverage Δ	Complexity Δ
...or/ipc/netty/http/client/HttpClientOperations.java	55.78% <100%> (+1.17%)	78 <1> (+3)	⬆️
...or/ipc/netty/http/server/HttpServerOperations.java	71.05% <100%> (+1.16%)	56 <2> (+3)	⬆️
...in/java/reactor/ipc/netty/http/HttpOperations.java	68.83% <100%> (-0.4%)	22 <0> (-1)
...java/reactor/ipc/netty/http/server/HttpServer.java	90.1% <76.19%> (-4.34%)	20 <5> (+5)
...actor/ipc/netty/http/server/HttpServerOptions.java	98.63% <87.5%> (-1.37%)	15 <1> (+1)
src/main/java/reactor/ipc/netty/FutureMono.java	86% <0%> (+4%)	6% <0%> (+1%)	⬆️
.../ipc/netty/channel/PooledClientContextHandler.java	68.06% <0%> (+5.04%)	27% <0%> (+2%)	⬆️
...tor/ipc/netty/channel/CloseableContextHandler.java	57.89% <0%> (+5.26%)	9% <0%> (+1%)	⬆️
... and 1 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 015c89b...ac88385. Read the comment docs.