Migrates token relay from spring-cloud-security.

[spencergibb]

Adds refresh token support.

Fixes spring-attic/spring-cloud-security#175

Fixes gh-1975

See spring-attic/spring-cloud-security#231

[codecov]

Codecov Report

Merging #1976 into master will increase coverage by 0.12%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #1976      +/-   ##
============================================
+ Coverage     77.24%   77.36%   +0.12%     
- Complexity     1250     1263      +13     
============================================
  Files           162      164       +2     
  Lines          4768     4790      +22     
  Branches        388      388              
============================================
+ Hits           3683     3706      +23     
  Misses          880      880              
+ Partials        205      204       -1     

Impacted Files	Coverage Δ	Complexity Δ
.../gateway/security/TokenRelayAutoConfiguration.java	100.00% <100.00%> (ø)	3.00 <3.00> (?)
...teway/security/TokenRelayGatewayFilterFactory.java	100.00% <100.00%> (ø)	8.00 <8.00> (?)
...eway/filter/factory/RetryGatewayFilterFactory.java	77.97% <0.00%> (+0.59%)	38.00% <0.00%> (+2.00%)

---

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 b12a5f2...7620023. Read the comment docs.