Publish core artifacts continuously via Travis CI

The Travis CI build now publishes ethereumj-core artifacts (classes,
sources and javadoc jars) on every push to master. See updated
ethereumj-core/README.md for details. Note that the `gradle release`
task has been renamed to `gradle publish`.

.travis.yml

@@ -4,6 +4,9 @@ jdk: oraclejdk8
 env:
   - JAVA_OPTS ="-XX:+UseConcMarkSweepGC -XX:+CMSClassUnloadingEnabled -XX:PermSize=256M -XX:MaxPermSize=512M"
 
+script:
+  - ./gradlew build publish
+
 after_success:
   - ./gradlew jacocoTestReport coveralls
 
@@ -18,3 +21,11 @@ notifications:
     on_failure: always
     use_notice: true
     skip_join: true
+
+# Encrypted ORG_GRADLE_PROJECT_bintrayUser and ORG_GRADLE_PROJECT_bintrayKey env key/value pairs for use by Travis when
+# authenticating against oss.jfrog.org and/or Bintray repositories. See http://docs.travis-ci.com/user/encryption-keys
+# http://www.gradle.org/docs/current/userguide/tutorial_this_and_that.html#sec:gradle_properties_and_system_properties
+env:
+  global:
+    secure: "BSdfBQsJi5VFcIF7Z50ddfjex60OZpd8OM7AxN+h93wxzBx/GD2bsWA9elwvrLFImByw5RIqE9xRvL4CioKZLgFiJCSFuPkf6I+6R6PsUhqklPvAJSXHlQXOM6bJD23rZewyfudh5JtqADVavY7vlXnmYXFeWKh8XdPYtRPlJV0="
+    secure: "iZcZikUHrdaxsc5at1KT0M/6D4OHdU2WTd/aFIBKERXteGw+okq+s+VWghnELEq3YsKfYRJrkslcA6Mpcxq7KrUMsSSX1kZ1ifsk2151sU3+fJpIYQ9pCeWboLWSF//A7IdEe+zHpRVFuHVGU05OAalNCmJ52TEe3/M0YkY5+e8="

ethereumj-core/README.md

@@ -59,6 +59,4 @@ Run `../gradlew install`.
 
 #### Publish ethereumj-core builds
 
-Push to master.
-
-Run `../gradlew release`. Snapshots will be published to oss.jfrog.org; releases will be published to Bintray. You must supply the `bintrayUser` and `bintrayKey` properties to the Gradle build in order to authenticate. Do this in $HOME/.gradle/gradle.properties for greatest convenience and security.
+Simply push to master, and [the Travis CI build](https://travis-ci.org/ethereum/ethereumj) will take care of the rest. To publish manually instead, just run `../gradlew publish`. Where the artifacts are published depends on the value of the `version` property in the [root build.gradle file](../build.gradle). Snapshots (version values ending in `-SNAPSHOT`) will be published to oss.jfrog.org, while releases will be published to Bintray (and subsequently to JCenter). **You must be a member of the [ethereum Bintray organization](https://bintray.com/ethereum) and you must supply `bintrayUser` and `bintrayKey` properties to the Gradle build in order to authenticate against these repositories**. Configure these properties in your `$HOME/.gradle/gradle.properties` for greatest convenience and security.

ethereumj-core/build.gradle

@@ -154,7 +154,7 @@ bintrayUpload.onlyIf {
     (!pullRequest || pullRequest == 'false') && !project.version.endsWith('-SNAPSHOT')
 }
 
-task release {
-    description = "Releases snapshot versions to oss.jfrog.org and releases to Bintray"
+publish {
+    description = "Releases snapshots to oss.jfrog.org and releases to Bintray/JCenter"
     dependsOn artifactoryPublish, bintrayUpload
 }