fix geth startup in docker-compose

[sznicolas]

Two things fixed in this PR:

1. As purposed ualtinok in PR Fix host_network port_bindings incompatibility #21 , removal of network_mode="host"
2. geth starts before geth_init has exited. Its logs says :
   Fatal: Failed to create the protocol stack: datadir already used by another process
   Can be solved by adding a condition in the depends_on.

[O1ahmad]

Definitely simpler to use host network mode here rather than listing all ports (so uber nit/probably outside the design) but wondering what the thought is with something like: https://github.com/0x0I/container-file-geth/blob/master/compose/docker-compose.yml#L21 to potentially avoid local port conflicts and enable port customization.

Could be not worth having to think about tho the defaults basically yield the same result as host networking and each envvar can also just be set within the operator's runtime env (e.g. via something like export rpc_port=8545) or either set within a .env file processed by default or a custom file passed with docker-compose up provided alternate host ports are desired.