Corrected creation of log files

This was caused by the confusion stemming from the OpenOptions::append
documentation, bugged here:
rust-lang/rust#44432

Author: mqudsi

src/main.rs

@@ -103,7 +103,7 @@ fn main() {
 
     //initialize logger
     if let Some(ref p) = moptions.log {
-        logfile = match std::fs::OpenOptions::new().append(true).open(&p) {
+        logfile = match std::fs::OpenOptions::new().create(true).append(true).open(&p) {
             Err(e) => {
                 eprintln!("Could not create log file: {}", e.description());
                 std::process::exit(-1);
@@ -183,11 +183,11 @@ fn relaunch<L>(loptions: &LaunchOptions, moptions: &MonitorOptions, mut logger:
         cmd.args(&loptions.args);
 
         if let Some(ref path_stdout) = moptions.stdout {
-            let stdout = OpenOptions::new().append(true).open(path_stdout).map_err(|e| RelaunchError::StdoutErr(e))?;
+            let stdout = OpenOptions::new().create(true).append(true).open(path_stdout).map_err(|e| RelaunchError::StdoutErr(e))?;
             cmd.stdout(stdout);
         }
         if let Some(ref path_stderr) = moptions.stderr {
-            let stderr = OpenOptions::new().append(true).open(path_stderr).map_err(|e| RelaunchError::StderrErr(e))?;
+            let stderr = OpenOptions::new().create(true).append(true).open(path_stderr).map_err(|e| RelaunchError::StderrErr(e))?;
             cmd.stderr(stderr);
         }