Update openapi spec

[bretterer]

• Updates to latest spec (See changelog for details)
• Moved all generated files to root level instead of Generated folder and namespace
• Update to allow for use of setAcceptType and setContentType headers
• Updated travis php versions to test
• Changed phpcs (php code style) to ignore line length due to comments

[codecov-commenter]

Codecov Report

Merging #88 into sdk_v2 will decrease coverage by 56.14%. The diff coverage is 50.27%.

@@              Coverage Diff              @@
##             sdk_v2      #88       +/-   ##
=============================================
- Coverage     92.53%   36.38%   -56.15%     
- Complexity      950     2080     +1130     
=============================================
  Files           131      272      +141     
  Lines          2959     7656     +4697     
=============================================
+ Hits           2738     2786       +48     
- Misses          221     4870     +4649     

Impacted Files	Coverage Δ	Complexity Δ
...rc/Applications/AuthorizationServerCredentials.php	0.00% <0.00%> (ø)	2.00 <2.00> (?)
src/Applications/Csr.php	0.00% <0.00%> (ø)	4.00 <3.00> (?)
src/Applications/CsrMetadata.php	0.00% <0.00%> (ø)	4.00 <4.00> (?)
src/Applications/CsrMetadataSubject.php	0.00% <0.00%> (ø)	12.00 <12.00> (?)
src/Applications/CsrMetadataSubjectAltNames.php	0.00% <0.00%> (ø)	2.00 <2.00> (?)
src/Applications/JwkUse.php	0.00% <0.00%> (ø)	2.00 <2.00> (?)
src/Applications/OAuth2Actor.php	0.00% <0.00%> (ø)	3.00 <1.00> (?)
src/Applications/OAuth2Claim.php	0.00% <0.00%> (ø)	20.00 <20.00> (?)
src/Applications/OAuth2ClaimConditions.php	0.00% <0.00%> (ø)	2.00 <2.00> (?)
src/Applications/OAuth2Client.php	0.00% <0.00%> (ø)	5.00 <5.00> (?)
... and 443 more

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