Clean up import chain and support @import umbrella header.

- Moved constants declared in TSKTrustKitConfig.h into
TSKTrustKitConfig.m, instead of TrustKit.m.
- Bump version to 1.5

TrustKit.podspec

@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name         = "TrustKit"
-  s.version      = "1.4.2"
+  s.version      = "1.5.0"
   s.summary      = 'TrustKit is an open source framework that makes it easy to deploy SSL pinning in any iOS, macOS, tvOS or watchOS App.'
   s.homepage     = "https://datatheorem.github.io/TrustKit"
   s.documentation_url = 'https://datatheorem.github.io/TrustKit/documentation/'
@@ -13,9 +13,15 @@ Pod::Spec.new do |s|
   s.tvos.deployment_target = '10.0'
   s.watchos.deployment_target = '3.0'
 
-  s.source_files = 'TrustKit', 'TrustKit/**/*.{h,m,c}'
+  s.source_files = ['TrustKit', 'TrustKit/**/*.{h,m,c}']
   s.header_mappings_dir = 'TrustKit'
-  s.public_header_files = 'TrustKit/TrustKit.h', 'TrustKit/TSKPinningValidator.h'
-  s.frameworks = 'Foundation', 'Security'
+  s.public_header_files = [
+    'TrustKit/TrustKit.h',
+    'TrustKit/TSKTrustKitConfig.h',
+    'TrustKit/TSKPinningValidator.h',
+    'TrustKit/TSKPinValidatorResult.h',
+    'TrustKit/Pinning/TSKPublicKeyAlgorithm.h'
+  ]
+  s.frameworks = ['Foundation', 'Security']
   s.requires_arc = true
 end