Gradle dependency import should honor file name

When importing dependencies from Gradle Intellij identifies them by 'groupId:artifactId:version[:classifier]'. While being sufficient for conventional layouts, it still may fail with custom Ivy repositories. Consider the following example:
```groovy
apply plugin: 'java'
repositories {
    ivy {
        ivyPattern 'http://teamcity.jetbrains.com/guestAuth/repository/download/[module]/[revision]/teamcity-ivy.xml'
        artifactPattern 'http://teamcity.jetbrains.com/guestAuth/repository/download/[module]/[revision]/[artifact](.[ext])'
    }
}

dependencies {
    compile ( 'org:bt345:lastSuccessful' ){
        artifact {
            name = 'kotlin-compiler-0.9.712'
            type = 'zip'
        }
    }
    compile ( 'org:bt345:lastSuccessful' ){
        artifact {
            name = 'kotlin-compiler-for-maven'
            type = 'jar'
        }
    }
} 
```
Upon import Intellij creates only one of these deps, ignoring the second one as a duplicate. Proposed fix addresses the problem by appending a filename for dependencies which does not follow Maven naming convention.