Improve syntax for specifying file mounts

[kewegner]

This issue has to do with the fact that:

1. Windows path names are likely to include the drive ID and a colon separator

2. Even Unix-style path and file names are allowed to include colons (try touch foo:bar and you'll see what I mean).

For now:

1. We mount volumes with -v : which won't work in case has a colon in it. We need to switch to the --mount syntax (or use the Go Docker APIs appropriately).

2. The issue is been fixed "for Windows" - assuming that the only extra colon we get can occur after the drive ID (i.e. C:/:).

3. The controller also has this issue when it defaults the WATCH_DIR from MOUNTS

@kylegc did a little more research on this and discussed with @chilanti . Even if we switch to the --mount syntax, we still have the issue of splitting the list of mounts with the ';' separator char.

The Ultimate solution is as follows:

1. Allow either docker -v or --mount syntax in APPSODY_MOUNTS var with a default separator of ';'. We can determine that --mount syntax is used if "src=" and "dst=" exist.
2. We provide an optional APPSODY_SEPARATOR var that allows the user to change the default separator of ';' to any string sequence they'd like.

Until this solution is implemented, it will be documented that ':' and ';' characters are not supported in the mount paths.